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DCE - 2005* 1. How many number of atoms are present in F.C.C. unit cell? (a) 4 (b) 3 (c) 2 (d) 1. 2. (a) (b) (d)
The H-spectrum show Heisenberg's uncertainty principle diffraction (c) polarisation presence of quantised energy level.
3. The sublimation energy of I 2 ( s) is 57.3 kJ/mol and the enthalpy of fusion is 15.5 kJ/mol. The enthalpy of vaporisation of I 2 is (a) 41.8 kJ/mol (b) - 4 1 . 8 kJ/mol (c) 72.8 kJ/mol (d) -72.8 kJ/mol. 4. The correct order of pseudohalide, polyhalide and interhalogen are (a) B r V , OCN , IF5 (b) IF5, Brl2", OCN" (c) OCN~, IF5, Brlj (d) OCN", Brl2", IFS.
20. [Fe(N0 2 ) 3 Cl 3 ] and [Fe(0 - NO) 3 Cl 3 ] shows (a) linkage isomerism (b) geometrical isomerism (c) optical isomerism (d) none of these. 11. A certain compound gives negative test with ninhydrin and positive test with Benedict's solution. The compound is (a) a protein (b) a monosaccharide (c) a lipid (d) an amino acid. 12. Which of the following gives iodoform test? (a) CH3 - CH 2 (OH) (b) C 2 H 5 CHO (c) (CH 2 OH) 2 (d) none of these. 13. For equilibrium reaction, value of Gibbs free energy change is (a) > 0 (b) < 0 (c) = 0 (d) * 0. 14. In the reaction,
5. When 2-butyne is treated with Pd-BaS0 4 ; the product formed will be (a) c/s-2-butene (b) /ra«s-2-butene (c) 1-butene (d) 2-hydroxy butane.
C H 3 - C = C - C H 3 (OX > CH, - C - C - CH, 3 (ii) H20/Zn llll o o X is (a) HN0 3 (b) 0 2 (d) KMn0 4 . (c) 0 3
6. The rate constant for a chemical reaction has units L mol~' s - 1 , order of the reaction will be (a) 0 (b) 1 (c) 2 (d) 3.
15. Xis dissolved in water. Maximum boiling point is observed when J f i s .... (0.1 M each) (a) CaS0 4 (b) BaCl 2 (c) NaCl (d) urea.
7. Buna-S is a polymer of (a) butadiene only (b) butadiene and styrene (c) styrene only (d) butadiene and nitryl.
16. On adding 0.1M solution each of [Ag+], [Ba+], [Ca+] in a Na 2 S0 4 solution, species first precipitated is [Kv, BaS0 4 = 1 0 " " , K,p CaS0 4 = 10"6, K,„ Ag 2 S0 4 = lO"5] (a) Ag 2 S0 4 (b) BaS0 4 (c) CaS0 4 (d) all of these.
8. Least paramagnetic property is shown by (a) Fe (b) Mn (c) Ni (d) Cu. Maximum enol content is in O O (a) ^
O
17. Penetrating power of waves are (a) y > a > 0 (b) y < « > P (c) y > X-rays > a (d) y < a < p.
o
o
18. Which of the following statements does not form a part of Bohr's model of hydrogen atom?
9.
o
("»
s KH
CHEMISTRY TODAY | AUGUST '05
H
* based on memory 35
(a) energy of the electrons in the orbit is quantised (b) the electron in the orbit nearest the nucleus has the lowest energy (c) electrons revolve in different orbits around the nucleus (d) the position and velocity of the electrons in the orbit cannot be determined simultaneously. 19. Electrons will 1st enter into the set of quantum numbers n = 5, I = 0 or n = 3, I = 2 (a) n = 5, / = 0 (b) both possible (c) n = 3, / = 2 (d) data insufficient. 20. Which of the following is most reactive towards nucleophilic substitution reaction? (a) CH 2 = CH - CI (b) C 6 H 5 C1 (c) CH 3 CH = CHC1 (d) C1CH2 - CH = CH 2 21. For the reaction 2H 2 + 0 2 -> 2H z O, AH = - 5 7 1 . Bond energy of H - H = 435, 0 = 0 = 498, then calculate the average bond energy of O - H bond using the above data. (a) 484 (b) - 484 (c) 271 (d) - 2 7 1 . 22. Calculate the volume of H 2 gas at NTP obtained by passing 4 amperes through acidified H 2 0 for 30 minutes is (a) 0.0836 L (b) 0.0432 L (c) 0.1672 L ' (d) 0.836 L. 23. Propyne and propene can be distinguished by (a) conc. H 2 S 0 4 (b) Br 2 in CC14 (c) alk. K M n 0 4 (d) A g N 0 3 in NH 3 . Lindlar's
24. IA] I 2 W ; AH2 = + 15.5 kJ/mol The enthalpy of vaporisation of I2 = AHi - AH2 = 57.3 - 15.5 = + 41.8 kJ/mol. 4. (d) : A few ions, consisting of two or more electronegative atoms of which at least one is nitrogen, that have properties similar to those of halide ions, are called pseudohalide ions. e.g. OCN~. Halide ions often react with molecules of halogens or interhalogen and form polyhalide ions. e.g. Brl2". The halogens, on account of difference in their electronegativities, combine with each-other and form binary covalent compounds of AB„ type which are called interhalogen compounds. A is always bigger atom and B is smaller atom and n may have values 1, 3, 5 and 7 corresponding to oxidation states of halogens, e.g. IF5. 5.
Pd
(a) : H,C - C = C - CH, 2-butyne
-BaS% CH,
/CHj
/
H'
\
H
c/s-2-butene
Selective reduction from ( = ) bond to ( = ) bond which is syn type. 6. (c) : Litre mol -1 time -1 is the unit for second order reactions. 7. (b) : Buna-S rubber is a co-polymer of three moles of butadiene and one mole of styrene. CH -- CH, nCII, = CH - C H = CH2 + n [ Q 1,3-butadiene
styrene
• CH2 - CH = CH - CH2 - CH - CH, -
8. (d) : 25 Mn —» 3id s , 4s2, number of unpaired electrons = 5 6 2 26Fe —> 3d , 4s , number of unpaired electrons = 4 2 28 Ni —> 3 cP, 4s , number of unpaired electrons = 2 w 1 29Cu —> 3 d , 4s , number of unpaired electrons = 1 Paramagnetic character depends upon number of unpaired electrons. 9.
(c): o
o
H v - U O UOT t H-i
i ^ - V j i CH3 — C — CH, — C — CH3 CH 3 -C = C H - C - C H 3 acetylacetone (keto form, 24%)
(enolic form, 76%)
A V O
H-O
If the enolic form besides H-bonding is also stabilised by conjugation (i.e. enolic double bond is in conjugation with a multiple bond or a benzene ring), the enol content further increases. 10. (a) : This type of isomerism occurs in complex compounds which contain ambidentate ligands like N0 2 ", SCN", CN", S 2 0 3 2 - and CO. These ligands have two donor atoms but at a time only one atom is directly linked to the central metal atom of the complex, e.g. [Fe(N0 2 ) 3 Cl 3 ] and [Fe(ONO) 3 Cl 3 ] are linkage isomers as N0 2 " is linked through O. 11. (b): Since it gives a negative test with ninhydrin, it cannot be a protein or an amino acid. Since it gives a positive test with Benedict's solution, it must be a monosaccharide but not a lipid. 12. (a) : Iodoform test is exhibited by ethyl alcohol, acetaldehyde, acetone, methyl ketones and those alcohols which possess CH 3 CH(OH) - groups. OH CH3CH - H + 41, + 6NaOH ethyl alcohol
13. (c) AH AH :. AG
CHI3 + 5NaI
iodoform + HCOONa + 5H 2 0
:At equilibrium, = positive and TAS = positive and = TAS. = AH - TAS = 0.
14. (c) : 0 3 converts alkynes to 1,2-diketones. 15. (b) : Elevation in boiling point is a colligative property which depends upon the number of
buna-S CHEMISTRY TODAY
AUGUST '05
37
molecules/ions. Higher the number of ions, greater will be elevation in boiling point. -5
16. (a) : [S0 4 2 "] in Ag 2 S0 4 [S042~] in BaS0 4 = [S042~] in CaS0 4 =
.-11
10"
0.1
10- 6 0.1
10" - = 0.1x0.1
10"
= 10- 1 0 - = 10i-5
As the ionic product of BaS0 4 is less i.e. Ba2+ will be precipitated first.
23. (d) Reaction with
Propene
Propyne
(a) conc. H 2 S0 4 addition addition (b) Br2 in CCl4 decolourises decolourises (c) alk. KMn0 4
decolourises decolourises (oxalic acid is (glycol is formed) formed)
(d) AgN0 3 in NH 3
no reaction
17. (c) : Absorption increases with increase in wavelength very fastly. y-rays have very higher energy and very short X, i.e. penetration is very higher. It passes through concrete. X-rays will pass through metal sheets, a-rays are just the nuclei of helium atom that can be stopped by even a paper. (3-rays are stopped by Al foils. Y > A'-ray > (3 > a
2CH3C = CH + AgN0 3 + 2NH40H —> 2CH3C = CAg + 2NH 4 N0 3 + 2H 2 0
18. (d) : (d) is uncertainty principle and not Bohr's postulate. 19. (c): The order of energies and hence that of filling of orbitals can be calculated by (n +1) rule which states as follows: (i) Orbitals are filled in order of increasing (n + I) values. (ii) If two orbitals have the same {n + I) value, the orbital with lower value of n is filled first. Thus, n = 3 will be filled first. 20. (d): Ally I chloride > vinyl chloride > chlorobenzene 21. (a) : A//reaction = 2 * B.E. (H2) + B.E. (0 2 ) - 2 x B.E. (H 2 0) - 571 = 2 x 435 + 498 - 2 x B.E. (H 2 0) - 571 = 870 + 498 - 2 x B.E. (H 2 0) - 2 x B.E. (H 2 0) = -571 - 1368 = - 1939. B.E. (H 2 0) = 1939/2 = 969.5
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969.5 B.E. (O - H) = —^— = 484.75 22. (d) : O = 4 x 30 x 60 C H,0
1 H,2 + - O 2, 2
2H + + 1e -> H2 (1 mole) (i.e. 22400 cc at NTP) IF = 2 x 96500 C 4 x 30 x60 C will give H2
42
22400x4x30x60 2x96500 = 835.64 cc = 0.836 L.
/
1
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III •Of
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24. (a): Alkynes give different products with different reducing agents. With Lindlar's catalyst (i.e. Pd deposited over BaS0 4 or CaC0 3 and partially poisoned by lead acetate, sulphur or quinoline) or nickel boride (also called P-2 catalyst), cw-alkenes are formed but with Na in liquid NH 3 at 200 K (Birch reduction) /nmy-alkenes are formed. CH,
V
/ C = c
/
.CH,
Lindlar's catalyst
x
CH, - C = C - CH3 N a in liq. N H 3
ew-butene
(A)
CH, H
/H
in comparison to 2 M urea solution. So 1 M glucose solution has minimum osmotic pressure. 30. (a): The osmotic pressure of solution A is greater than B due to greater number of particles. 31. (a) : [Ag 2 O w ] = [Ag (s) ] = 1 Hence Kp = P0y 32. (c) : Both have linear structure. F-Xe-F, O = C =
0
33. (b) : Electron withdrawing groups increase the acidity while electron-donating groups decrease the acidity of phenols. OH OH OH OH
>c=cx
NO,
CH, If a bear in Yosemite, and one in Alaska fall into water, which one would dissolve faster? The bear in Alaska because it is polar. 'P Where does one put the In the zinc.
dishes?
> What do you call a tooth in a glass of water? One molar solution. y Why does hamburger have lower energy steak? Because it's in the g r o u n d state.
than
39
SOLVED PAPER
K E R A L A PET - 2005 1. 100 g CaC0 3 is treated with 1 litre of 1 N HC1. What would be the weight of C 0 2 liberated after the completion of the reaction? (a) 5.5 g (b) 11 g (c) 22 g (d) 33 g (e) 44 g. 2. The relationship between the energy of the radiation with a wavelength 8000 A and the energy E2 of the radiation with a wavelength 16000 A is (a) £ , = 6E 2 (b) E} = 2E2 (c) = 4E 2 (d) £, = 1/2 E2 (e) = E2. 3. If the molecule of HC1 were totally polar, the expected value of dipole moment is 6.12 D (debye), but the experimental value of dipole moment was 1.03 D. Calculate the percentage ionic character. (a) 17 (b) 83 (c) 50 (d) zero (e) 90. 4. Which one of the following molecules has the smallest bond angle? (a) NH 3 (b) PH 3 (c) H 2 0 (d) H 2 Se (e) H 2 S. 5. If the absolute temperature of a gas is doubled and the pressure is reduced to one half, the volume of the gas will be (a) remain unchanged (b) be doubled (c) increase fourfold (d) be halved (e) be reduced to one-fourth. 6. To what temperature must a neon gas sample be heated to double pressure, if the initial volume of gas at 75°C is decreased by 15.0%? (a) 319°C (b) 592°C (c) 128°C (d) 60°C (e) 90°C. 7. When electric current is passed through an ionic hydride in molten state 42
(a) (b) (c) (d) (e)
hydrogen is liberated at anode hydrogen is liberated at cathode no change takes place hydride ion migrates towards cathode hydride ion remains in solution.
8. Li, (a) (c) (e)
The order of first ionization energies of the elements Be, B, Na is Li > Be > B > Na (b) Be > B > Li > Na Na > Li > B > Be (d) Be > Li > B > Na B > Be > Li > Na.
9. The froth-floatation process is based upon (a) the difference in the specific gravity of ore and gangue particles (b) the magnetic properties of gangue and ore (c) preferential wetting of gangue particles by oil (d) preferential wetting of ore particles by oil (e) the solubility of ore particles in suitable reagent. 10. Which one of the following statements is true for all the alkali metals? (a) their nitrates decompose on heating to give N 0 2 and 0 2 (b) their carbonates decompose on heating to give C0 2 and the metal oxide (c) they react with oxygen to give mainly the oxide M20 (d) they react with halogens to give the halides MX (e) they react with nitrogen to give nitrides. 11. (a) (b) (c) (d) (e)
The order of acidic strength of boron trihalides is BF3 < BC13 < BBr 3 < BI3 BI3 < BBr3 < BC13 < BF 3 BC13 < BBr 3 < BI3 < BF 3 BBr 3 < BC13 < BF3 < BI3 BF3 < BI3 < BC13 < BBr 3 .
12. is (a) (c) (e)
The carbide which reacts with water to form propyne CaC 2 Mg 2 C 3 Be 2 C.
(b) SiC (d) A14C3
CHEMISTRY TODAY | AUGUST '05 40
13. (a) (c) (e)
Effective magnetic moment of Sc3+ ion is 1.73 (b) 0 5.92 (d) 2.83 3.87.
14. Potassium permanganate acts as an oxidant in alkaline and acidic media/The final products formed from KMn0 4 in the two conditions are respectively (a) Mn0 2 ~ and Mn 3+ (b) Mn 3+ and Mn 2+ (c) Mn 2+ and Mn 3+ (d) Mn0 2 and Mn 2+ (e) Mn 2+ and Mn0 2 . 15. Calculate the mass loss in the following. ,2H + -> 2He + \n (Given the masses : 2H = 2.014; 3 H = 3.016, He = 4.004, n = 1.008 amu) (a) 0.018 amu -(b) 0.18 amu (c) 0.0018 amu (d) 1.8 amu (e) 18 amu. 16. Match list I and list II and select the correct answer using the code given below the lists. List I List II Nuclear reactor Substance used components 1. Moderator A. Uranium 2. Control rods B. Graphite 3. Fuel rods C. Boron 4. Coolant D. Lead E. Sodium. Codes : (a) 1-B, 2-A, 3-C, 4-E (b) 1-B, 2-C, 3-A, 4-E (c) 1-C, 2-B, 3-A, 4-E (d) 1-C, 2-D, 3-A, 4-B (e) 1-D, 2-C, 3-B, 4-A. 17. AH and AS for a reaction are +30.558 kJ mol"1 and 0.066 k JKr1 moL1 at 1 atm pressure. The temperature at which free energy change is equal to zero and the nature of the reaction below this temperature are (a) 483 K, spontaneous (b) 443 K, non-spontaneous (c) 443 K, spontaneous (d) 463 K, non-spontaneous (e) 463 K, spontaneous. 18. What would be the heat released when an aqueous solution containing 0.5 mole of HN0 3 is mixed with 0.3 mole of OH~ (enthalpy of neutralisation is -57.1 kJ)? (a) 28.5 kJ (b) 17.1 kJ (c) 45.7 kJ (d) 1.7 kJ (e) 2.85 kJ. 19. Am + 3 BQ,) '(g) ^
4C(i,). Initial concentration of A
CHEMISTRY TODAY | AUGUST '05
is equal to that of B. The of A and C are equal. Kc (a) 0.08 (c) 8 (e) 1/8.
equilibrium concentrations = (b) 0.8 (d) 80
20. Two moles of PCI5 is heated in a closed vessel of 2 litre capacity. When the equilibrium is attained 40% of it has been found to be dissociated. What is the Kc. in mol/dm 3 ? (a) 0.532 (b) 0.266 (c) 0.133 (d) 0.174 (e) 0.25 21. Dry air is passed through a solution containing 10 g of a solute in 90 g of water and then through pure water. The loss in weight of solution is 2.5 g and that of pure solvent is 0.05 g. Calculate the molecular weight of the solute? (a) 50 (b) 180 (c) 100 (d) 25 (e) 51. 22. The v a n ' t H o f f factor for BaCl 2 at 0.01 M concentration is 1.98. The percentage of dissociation of BaCl 2 at this concentration is (a) 49 (b) 69 (c) 89 (d) 98 (e) 100. 23. The standard electrode potentials of Ag + /Ag is + 0.80 V and Cu + /Cu is +0.34 V. These electrodes are connected through a salt bridge and if (a) copper electrode acts as a cathode, then E°ce]] is + 0.46 V (b) silver electrode acts as anode, then £°cen is - 0.34 V (c) copper electrode acts as anode then £° c d l is +0.46 V (d) silver electrode acts as a cathode then E°ceu is - 0.34 V (e) silver electrode acts as anode and £° cel! is +1.14 V. 24. In alkaline medium C10 2 oxidises H 2 0 2 to 0 2 and itself gets reduced to CI". How many moles of H 2 0 2 are oxidised by 1 mole of C10 2 ? (a) 1.0 (b) 1.5 (c) 2.5 (d) 3.5 (e) 5.0 25. For the reaction : 2N 2 0 5 4N0 2 fc) + 0 2 if the concentration of NO, increases by 5.2 x 10~3 M in 100 seconds then the rate of the reaction is 41
(a) 1.3 x 10"5 Ms"1 (c) 7.6 x 10"4 Ms"1 (e) 2.5 x 10"5 Ms"1
(b) 5 x 10"4 Ms"1 (d) 2 x 10-3 Ms"1
26. A first order reaction is 10% complete in 20 min. The time taken for 19% completion is (a) 30 min (b) 40 min (c) 50 min (d) 38 min (e) 45 min. 27. Lyophilic sols are more stable than lyophobic sols because the particles (a) are positively charged (b) are negatively charged (c) are solvated (d) repel each other (e) are heavy. 28. Potassium stearate is obtained by the saponification of an oil or fat. It has the formula CH 3 - (CH2)16 - COO"K+. The molecule has a lyophobic end (CH 3 ) and a lyophilic end COO~K+. Potassium stearate is an example for (a) lyophobic colloid (b) lyophilic colloid (c) multimolecuiar colloid (d) macromolecular colloid (e) associated colloid or micelle. 2 9 . (i) K 4 [ F e ( C N ) 6 ] (iii) K 3 [ C O ( C N ) 6 ]
32. How much of sulphur is present in an organic compound, if 0.53 g compound gave 1.158 g of BaS0 4 on analysis? (a) 10% (b) 15% (c) 20% (d) 25% (e) 30%. 33. An alkene having the molecular formula C 9 H 18 on ozonolysis gives 2,2-dimethyl propanal and 2-butanone. The alkene is (a) 2,2,4-trimethyl-3-hexene (b) 2,2,6-trimethyI-3-hexane (c) 2,3,4-trimethyl-2-hexene (d) 2,2,4-trimethyl-2-hexene (e) 2,2-dimethyl-3-heptene. 34. Observe the following reactions and predict the nature of A and B.
(ii) K 3 [ C r ( C N ) 6 ] (iv) K 2 [ N i ( C N ) 4 ]
Select the complexes which are diamagnetic? (a) (i), (ii) and (iii) (b) (ii), (iii) and (iv) (c) (i), (iii) and (iv) (d) (i), (ii) and (iv) (e) (ii) and (iv). 30. Which is not true of the coordination compound [Co(en) 2 Cl 2 ]Cl? (a) exhibits geometrical isomerism (b) exhibits optical isomerism (c) exhibits ionisation isomerism (d) is an octahedral complex (e) is a cationic complex. 31. The IUPAC name of the compound is H O O C - CH, ~ CH - CH2 - CH2 - COOH COOH
(a) (b) (c) (d) (e) 42
2(carboxymethyl)-pentane-l,5-dioic acid 3-carboxyhexane-l,6-dioic acid butane-1,2,4-tricarboxyIic acid 4-carboxyhexane-l,6-dioic acid 1,2-dicarboxy-pentanoic acid.
35. Nitration of aniline in strongly acidic medium, results in the formation of w-nitroaniline also. This is because (a) amino group is meta orienting during electrophilic substitution reaction (b) nitro group goes always to the meta position irrespective of the substituents (c) nitration of aniline is a nucleophilic substitution reaction in strongly acidic medium (d) in strongly acidic conditions aniline is present as anilinium ion CHEMISTRY TODAY | AUGUST '05 42
(e) strong acids generate nitrite anion which can attack only the'meta position. 36. How toluene? (a) 3n + (c) 37t + (e) 6n +
many sigma and pi bonds are present in (b) 3% + 6 a (d) 6n + 3 a
8CT
10a 6g.
37. Which of the following Fischer's projection formula is identical to D-glyceraldehyde? CH2OH CH,OH -CHO
(a) OH-
OH
(b) H-
H CHO
CHO
...
H •CH2OH (e) HO-
• CH2OH CHO
38. The name of the compound is
(2Z, (2Z, (2E, (4E, (2E,
(i) diazotization
(ii)H3P02
HO
(a) (b) (c) (d) (e)
42. Which of the following does not undergo Cannizzaro's reaction? (a) benzaldehyde (b) 2-methylpropanal (c) jD-methoxybenzaldehyde (d) 2,2-dimethylpropanal (e) formaldehyde.
3,4,5-tribromoanihne —
H CHO (d) H-
OH
43. Identify the product in the following sequence.
• CHzOH
(c) HO-
41. CH 3 - CHO + HCN A. Compound A on hydrolysis gives (a) CH3 - C H 2 - C O O H (b) CH3 - CH 2 - CH2 - NH 2 (c) CH 3 - CO - COOH (d) CH 3 CO - CH = NOH (e) C H 3 - C H - C O O H
4Z)-2,4-hexadiene 4£)-2,4-hexadiene 4Z)-2,4-hexadiene 4Z)-2,4-hexadiene 4£)-2,4-hexadiene.
39. When 32.25 g of ethylchloride is subjected to dehydrohalogenation reaction the yield of the alkene formed is 50%. The mass of the product formed is (atomic mass of chlorine is 35.5). (a) 14 g (b) 28 g (c) 64.5 g (d) 56 g (e) 7 g. 40. Chlorination of toluene in presence of light and heat followed by treatment with aqueous NaOH gives (a) o-cresol (b) p-cresol (c) mixture of o-cresol and p-cresol (d) benzoic acid (e) 1,3,5-trihydroxy toluene. CHEMISTRY TODAY | AUGUST '05
(a) (b) (c) (d) (e)
„
^ ?
3,4,5-tribromobenzene 1,2,3-tribromobenzene 2,4,6-tribromobenzene 3,4,5-tribromonitrobenzene 3,4,5-tribromophenol.
44. Among the amines (i) C 6 H 5 NH 2 (ii) CH 3 NH 2 (iii) (CH 3 ) 2 NH (iv) (CH 3 ) 3 N the order of basicity is (a) (i) < (iv) < (ii) < (iii) (b) (iv) < (iii) < (ii) < (i) (c) (i) < (ii) < (iii) < (iv) (d) (ii) < (iii) < (iv) < (i) (e) (iv) < (iii) < (ii) < (i). 45. The number average molecular mass and mass average molecular mass of a polymer are respectively 30,000 and 40,000. The poly dispersity index of the polymer is (a) < 1 (b) > 1 (c) 1 (d) 0 (e) - 1 . 46. In biological systems, the RNA molecules direct the synthesis of specific proteins which are characteristics of each kind of organism. This process is known as (a) transcription (b) mutation (c) replication (d) translation (e) flocculation. 43
47. Pick up the correct statement. (a) CO which is major pollutant resulting from the combustion of fuels in automobiles plays a major role in photochemical smog (b) classical smog has an oxidising character while the photochemical smog is reducing in character (c) photochemical smog occurs in day time whereas the classical smog occurs in early morning hours (d) during formation of smog the level of ozone in the atmosphere goes down (e) classical smog is good for health but not photochemical smog. 48. In Antarctica ozone depletion is due to the formation of following compound. (a) acrolein (b) peroxy acetyl nitrate (c) S 0 2 and S0 3 (d) chlorine nitrate (e) formaldehyde. ANSWERS 1.
(c) : CaC0 3 + 2HC1 100 g
CaCl 2 + C 0 2 + H 2 0
2 N
44
100 g CaC0 3 with 2 N HC1 gives 44 g C 0 2 100 g CaC0 3 with 1 N HC1 will give 22 g C0 2 . 2.
(b) : E e= l/X 8000 _ 16000 E2
3.
16000 ,,
El=2E2.
8000
(a) : Percentage of ionic character experimental value of dipole moment XLOO theoretical value of dipole moment
= — x 100 = 16.83% « 17%. 6.12 4. (d) : NH 3 = 107°, PH 3 = 93°, H 2 0 = 104.5C H 2 Se = 91°, H 2 S = 92.5°. 5. (c) :Pl-P,Vl = V,T1 = T P2 = P/2, V2 = ?. T2 = 2T Applying gas equation, W _ PjV2 71 T2
6.
P2 = 2P, V2 =
85V
100 PxV _2Px85V 348 ~~ r 2 x l 0 0
42
PV
PR F, = 4 V. T 2T (a) : P{ = P, K, = V, Tx = 273 + 75 = 348 K or,
r, = ? r2
348x2x85 = 100
r 2 = 591.6 K = 318.6°C. 7. (a) : The electrolysis of the molten ionic hydride (LiH) yields hydrogen at anode. MH + H 2 0 MOH + H 2 T 8. (b) : In a period, the value of ionisation potential increases from left to right with breaks where the atoms have somewhat stable configurations. However, in a group, the ionisation potential decreases from top to bottom. Be B Li Na eV 9.3 8.3 5.4 5.1 9. (d) : Froth floatation process is based on the preferential wetting properties with the frothing agent and water. 10. (d) : (a) With the exception of LiN0 3 , the other nitrates decompose to nitrites and oxygen. 2MN0 3 2MN0 2 + 0 2 2LiN0 3 Li 2 0 + 2 N 0 2 + 1/2 0 2 (b) Since the alkali metals are highly electropositive, their carbonates are highly stable towards heat and readily soluble in water. Li 2 C0 3 decomposes on heating and insoluble in water. Li 2 C0 3 Li 2 0 + CO, (c) When heated in atmosphere of oxygen, the alkali metals ignite and form oxides. M-
M20 normal oxide (Li20)
O,
• M 2 0 2 — - > MO, peroxide
(Nap,)
(d) The alkali metals directly react with halogens forming the halides of the type MX. 2M + X 2 —» 2MX (e) Of the alkali metals, only lithium reacts with nitrogen and forms a nitride. 6Li + N 2 2Li 3 N 11. (a) : The relative strength of Lewis acids of boron trihalides increases in the order BF3 < BC13 < BBr 3 < BI3. This order can be explained on the basis of the tendency of the halogen atom to back donate its electrons to the boron atom and makes it less electron deficient. 12. (c) : Mg2C3 + 4H 2 0
CH 3 C =
CH + 2Mg(OH) 2
13. (b) : n e f f = > ( « + 2)B.M. where n = number of unpaired electrons. For Sc3+ = 3d 0 , n = 0. n = 0 CHEMISTRY TODAY | AUGUST '05
14. (d) : In alkaline medium, K M n 0 4 is first reduced to manganate and then to insoluble manganese dioxide. 2Mn(V + H20 2Mn02 + 20H" + 3[0] In acidic medium, manganous sulphate is formed. M n < V + 8H + + 5e~ Mn 2+ + 4 H 2 0 15. (a) : Mass loss = mass of reactants - mass of products = (2.014 + 3.016) - (4.004 + 1.008) = 5.030 - 5.012 = 0.018 amu. 16. (b) 17. (d) : AG = AH- TAS 0 = +30.558 - T x 0.066 or, T=
30.558 0.066
„„ = 463 K
If ( d G ) r P = 0, the sign ' = ' refers to a reversible process i.e. non-spontaneous. 18. ( b ) : 0.3 mole of OH" will neutralise only 0.3 mole of H N 0 3 . Heat evolved = 57.1 x 0.3 = 17.13 kJ. 19. (c) : A + 3 5
4C
a b a - x (b - 3x)
[C] 4
Kc =
0
4x
4x • 4x • 4jc • 4x
[A][Bf (a - x){b - 3x) Given a = b, a - x = 4x => a = 5x = b 4x•4x•4x•4x 4x•4x-4x-4x „ Kc = (5x-x)(5x-3 xy 4x-2x-2x-2x 20. (b) : According to Ostwald's dilution law, Kc =
a2 (l-a)F
0.40x0.40 (l-0.40)xl
10x18
m --
90 xm BaCl 2 11
22. (a) : Initial After disso.
2x2.5
2x250
0.05 Ba 2+ + 2C1"
1- a
0
0
a
2a
a =
1.98-1
=
0.98
= 0.49 2 2 For 1 mole, a = 0.49 0.49 For 0.01 mole, a = = 49. 0.01 23. (c) : The cell reaction is Cu w + 2Ag + Cu 2+ + 2Ag The two half cell reactions are Cu —» Cu 2+ + 2e~ Oxidation (anode) Ag + + e —> Ag Reduction (cathode) Ecew = Eox - £ r e d = 0.80 - 0.34 = +0.46 V. 24. (c) : C10 2 CL C10 2 + 2 H 2 0 + 5e CI" + 4 0 H " h2o2 o2 H202 + 20H0 2 + 2 H 2 0 + 2e C10 2 + 2H z O + 5e CI- + 40H~] x 2 H 2 Q 2 + 2QH0 2 + 2H 2 Q + 2e] x 5 2C10 2 + 5 H 2 0 2 + 2 0 H " 2C1" + 5 0 2 + 6 H 2 0 2C10 2 = 5H 2 0 2 C10 2 = 2.5 H 2 0 2 . 25. (a) : 2 N 2 0 5 ^ 4 N 0 2 (s) + 0 2 fe) Rate of the reaction with respect to N 0 2 i-3 5.2x10'
_ 14NQ2]_ 1 ~4
dt
X
100
- = 1.3xl0~ 5 Ms
26. (b) : For 1st case:
= 0.266.
, 2.303, 90 k= log 20 100 For Ilnd case : ,
k=
2.303,
log
(0
81
21. (c): Loss in weight of solution pressure of solution t 100 From eqn. (i), Loss in weight of solvent « p° - ps 2.303, . 9 0 2.303, 81 (•_• p° = vapour pressure of pure solvent) log = log 20 100 t 100 o loss in weight of solvent P -Ps 20(log81-logl00) 20(1.908-2) t = ps loss in weight of solution (log 9 0 - l o g 100) (1.954-2) P
-Ps
= 100.
Total = 1 - a + a + 2 a = 1 + 2 a . i = 1 + 2a
~ 4
a = 0.40, K = — = — = 1 litre. C Z/2 Kc =
0.05
wxM
20 x (-0.092)
mxW
(-0.046)
CHEMISTRY TODAY | AUGUST '05
(ii)
= 40 min.
45
27. ( c ) : Lyophilic sols are more stable than lyophobic sols because the residue left on evaporation can be readily transformed back into colloidal state simply by adding solvent.
1
2
3
4
COOH 32. (e) : Percentage of sulphur
29. (c) :
33. (a) : C9H18 + 0 3 -
[Fe(CN)6]4'
11 11 11
45
—
mass o f B a S O ,
X
-x 100
233
mass of organic compound
32 233
1.158-x 100 = 30%. 0.53 CH, • H,C - C - CHO 3
I
4p
CH 3
xx
XX X X
6
3-carboxyhexane-l,6-dioic acid
28. (e) : Substances w h o s e molecules aggregate spontaneously in a given solvent to form particles of colloidal dimensions are called associated colloids. The molecules of soaps and detergents are usually smaller than the colloidal particles. However, in concentrated solutions, these molecules associate and form aggregates of colloidal size. These aggregates of soaps or detergent molecules are called miscelles. 3d
5
31. (b) : HOOC - CH2 - CH - CH2 - CH2 - COOH
2,2-dimethylpropanal
+ CH3CH2COCH3 cP-sp3, diamagnetic
3d [Co(CN) 6 p-
11 11 11
45
4p
2-butanone
On the basis of product formation, the alkene must be
xx
XX X X
CH,
CH, I CH3 - C - H C = C - CH2CH3
cP-sp3, diamagnetic
3d [Ni(CN) 4 p-
45
CH3
4p
x x XX
11 11 11 11 XX
dsp1, diamagnetic
30. (c) : I o n i s a t i o n isomerism arises when the coordination compounds give different ions in solution, this condition is not satisfied with [Co(en) 2 Cl 2 ]Cl.
2,2,4-trimethyl-3-hexene
This is further confirmed by the reaction CH,
CH 3
CH,
CH 3 - C - H C = C - CH 2 CH 3 — C H
I
3
CH
C - HC ':;; CC CCH,CH,
I lil I •. i CH, o i l o
CH, -> CH3C-CHO +
O II CH 3 C-CH 2 CH 3
CH,
ci
-
1
CI
c/s-form trans-form Geometrical isomers
HBr
34. (c) :
> A
Formation of A shows electrophilic addition reaction, (i) HBr —> H + + B r
(») ©f
r\.
.CH =
CH
+ H+
> C 6 H 5 CHCH 3 Br J
CH «5-/-isomer optical isomers 46
[ o f
N
CH3
+
B r - _ >
( o T ^ (A)
CHEMISTRY TODAY | AUGUST '05
tor
HBr M)
(2)
Formation of B follows free radical addition reaction. hv (i) HBr - > H + Br (ii)
(2)
CHO
CHO
> B
( g p
O
interchange
• OH —
(4)H-
(1)
„
-OH
, „.. „ . > Cf 1,011H (4) CHO
(3) C H , O H
Br or, HO-
(iii)
[ O j ^
Br
38. (e) : If the atoms or groups of higher priority on each carbon atom of the double bond are on the opposite sides of the double bond, the configuration is designated as E and if they are on the same side, the configuration is designated as Z.
NH,
NH2 35. ( d ) :
H
©a.
+ HBr
HNO,
[Q]
• CH,OH
aniline p-nitroaniline
(51%)
(2E, 4£)-2,4-hexadiene
NFL
NH,
-HC1
39. (e) : C2H5C1
> C2H4
64.5
NO,
28
32.25
NO, m-nitroaniline (47%)
o-nitroaniline (2%)
This is due to the reason that under acidic conditions, protonation of the - NH 2 group gives anilinium cation
64.5 g C2H5C1 yields 28 g C 2 H 4 28x32.25 32.25 g C2H5C1 yields = — — — = 1 4 g C 2 H 4 As the yield is 50%, so the mass of alkene formed = 14/2 = 7 g. CH,
+
(NH 3 ) which is deactivating and /w-directing.
36. (c)
H C-H
40. (d) :
CH2C1
[O
high temp.
toluene
I
benzyl chloride
CHC1,
H
CC1, NaOH - > CsHsCOOH
CI,
IOct + 371
37. (c) : The configuration, in which OH group lies towards right and the H-atom towards left, the CHO lies at the top and CH 2 OH lies at the bottom of the Fischer projection, is called D-configuration. CHO H-
CI,
CI,
benzoic acid benzal chloride
benzo trichloride
OH 41. (e) : CHjCHO + HCN
r
> CH 3 C-CN H
•OH
(A) OH
CH2OH D-glyceraldehyde
CH3-C-COOH H
CHEMISTRY TODAY | AUGUST '05
47
42. (b): Aldehydes containing no a - H atoms on heating with concentrated alkali solution (50%) undergo Cannizzaro's reaction. In this reaction one molecule is oxidised at the expense of other which is reduced to alcohol. OCH, CH, I
C6H5CHO
CH 3 -CHCHO a-H atom
no a - H atom
CHO no a - H atom
CH, I
CH,C - CHO I
HCHO no a - H atom
CH3 no a - H atom
43. (b)
to the ability to form a peptide bond are exceedingly complex. The template for correct addition of individual amino acids is the wRNA, yet both /RNAs and rRNAs are involved in the process. The /RNAs carry activated amino acids into the ribosome which is composed of rRNA and ribosomal proteins. The ribosome is associated with the /kRNA ensuring correct access of activated /RNAs and containing the necessary enzymatic activities to catalyze peptide bond formation. 47. (c): Classical or London-type or sulphurous smogresults from a high concentration of sulphur oxides in the air and is caused by the use of sulphur bearing fossil fuels, particularly coal. Photochemical or Los Angeles-type smog - has its origin in the nitrogen oxides and hydrocarbon vapours emitted by automobiles and other sources which then undergo photochemical reactions in the lower atmosphere. Characteristics
Classical (London-type)
Photochemical (Los Angeles-type)
Primary pollutants
SOj, soot particles
NO*, organics
Secondary pollutants H 2 S 0 4 , 0 3 , PAN, organics, sulphate aerosol acids, aerosols etc. etc.
44. ( a ) : (CH 3 ) 2 NH > CH 3 NH 2 > (CH 3 ) 3 N > C 6 H S NH 2 iii > ii > iv > i This anomalous behaviour of tertiary amines is due to steric factors, i.e. crowding of alkyl groups cover nitrogen atom from all sides and thus makes the approach and bonding by a proton relatively difficult which results the maximum steric strain in tertiary amines. The electrons are there but the path is blocked, resulting the reduced in its basicity. In case of aniline, the phenyl group exerts - I (inductive) effect, i.e. it withdraws electrons. This results to the lower availability of electrons on nitrogen for protonation. 45. (b) : Number average molecular mass, M„ =30,000 Mass average molecular mass, Mw = 40,000 Mw __ 40,000 Poly dispersity index (PDI) = ^ ~ 3 Q Q ( ) 0 - = 1.33 46. ( d ) : Translation is the RNA directed synthesis of polypeptides. This process requires all three classes of RNA. Although the chemistry of peptide bond formation is relatively simple, the processes leading 42
Temperature
cool (< 35°F)
hot (> 75°F)
Relative humidity
high, usually foggy
low, usually hot and dry
Type of temperature inversion
radiation inversion
subsidence inversion
Time air pollution peaks
early morning
noon-evening
48. (d) : At higher altitudes inorganic chlorine is abundant, most of it in the form of HC1 or of chlorine nitrate, C10N0 2 . These are called "chlorine reservoirs"; they do not themselves react with ozone, but they generate a small amount of chlorine-containing radicals - CI, CIO, C10 2 and related species, referred to collectively as the 'C10 r family' - which do. An increase in the concentration of chlorine reservoirs leads to an increase in the concentration of the ozone - destroying radicals. Polar stratospheric clouds play a major role in the depletion of ozone layer, Antarctica by promoting the release of photolytically active chlorine from its reservoir species. HC1 + C10N0 2
CHEMISTRY TODAY | AUGUST '05 48
SOLVED PAPER
DPMT - 2005 1. Which of the following is not an actinide? (a) curium (b) californium (c) uranium (d) terbium 2. Europium is (a) s-block element (c)
(c) (CH3)2CHC2H5 H
< W >
/
(d) C H 3 C H - C H 3
'
(d) both (b) and (c).
42. Which will give chiral molecule?
C 2
h2O
CI CI I I (b) CH 3 CH 2 -C-CH 2 CH 3 (c) CH3CH2CH2CH,CH
I"1 s"1 1-' s"> I"1 s- 1 l"1 s"1.
41. Which of the following compounds will react with NaHC0 3 solution to give sodium salt and carbon dioxide? (a) acetic acid (b) w-hexanol
(a) CH3COCI
Mg/ether,
CI
• :— is
dt
40. Which of the following is paramagnetic? (a) N 2 (b) C 2 (c) N 2 + (d) 0 2 2 ".
( b )
(b) CH3COCI
d[B]
then (a) (b) (c) (d)
^
(a) CH3CH2CH2C1
Which statement is wrong for NO? it is anhydride of nitrous acid its dipole moment is 0.22 D it forms dimer (d) it is paramagnetic
45. Which of the following reactions will not give propane? 18 CHEMISTRY TODAY | SEPTEMBER '05
(d)
(o
< Q > - < 0 ^OH
49. There is no S - S bond in (a) S 2 0 4 2 " (b) S 2 O s 2 (c) S 2 0 3 2-
(d) s2o72-.
50. Which of the following is not a broad spectrum antibiotic? (a) tetracycline (c) penicillin
(b) Chloromycetin (d) none o f these.
SOLUTIONS 1. (d) : Terbium is lanthanide as it belongs to 4/-series having configuration [Xe] 4 f 9 6s2. However 19
the remaining members belong to 5/-series (actinides). 2. (d) : Europium is a/-block element as it follows the general electronic configuration of the/block element ( 4 / , - 1 4 5 d°>'6s2). Eu = [Xe] 4 / 7 6s2. 3.
(c) : Ax •Ap =
h 4ti
h Ax = 47t • mAv 4. ( b ) : The reaction of an alkyl halide or aryl halide with benzene in the presence of a Lewis acid, generally A1C13 is known as Friedel Craft's reaction. Ax • m • Av = — 471
5. (b) : Mg(OH), ^ Mg2+ + 20HKsp = [Mg2+] [OH-]2 1 X IO"12 = 0.01 [OH-]2 [OH-]2 = 1 x 10-10 [ O H ] = 10"5. + |4 5 9 [H ] = 10- /10- = IO" . pH = -log[H*] = —log[10 9] = 9. 6. (a) : Boyle's law - PV = constant On differentiating the equation, d(PV) = d(C) PdV + VdP = 0 dP _ dV VdP=-PdV P ~ V 7.
iT ^
\_
(b) : N = N0 ^ 2)
"
/• - \ 6
or,
>
u
N — = 2 Vo
-" U J -
12. (b) : According to Aufbau principle, electrons are filled into different subshells of an atom in order of their increasing energy, which means the subshell with lower energy is filled first. I s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d. 13. (b) : The formation of ionic bond depends upon easy formation of cation and anion. Therefore the ionisation energy value of the metal atom should be low, so that it can easily form cation. On the other hand, the electron affinity value of the non-metal atom should be high so that it can easily form anion. 14. (c) : HC1 and KOH both are strong. 15. (d) : Due to absence of ^-orbitals in N atom, it cannot accept electrons from H 2 0 for hydrolysis of NF3. 16. (a) : C0 2 is linear due to s/>-hybridisation. o=c—O 17. (b) : Equilibrium pressure = 3 atm NH 4 COONH 2 (.«) 2NH 3(K) + C0 2 ( S ) K
p = Pnh 3 ' Pco2 = 3" - 3 = 27.
18. (b) : Four 1° amines are possible. CH 3 CH 2 CH 2 CH 2 NH 2 , (CH 3 ) 2 CHCH 2 NH 2 , CH 3 CH(NH 2 )CH 2 CH 3 , (CH 3 ) 3 CNH 2 IfT6
,
19. (a) : Ecell = - 0 . 0 5 9 1 o g ^ Z J = -0.0591ogl0" 3 = - 0.059 x (-3) = 0.177 V.
n = 6.
64 T = tV2 * n = 2 x 6 = 1 2 hours. After 12 hours, sample became non-hazardous.
20. (d) : A radioisotope first emits a or P particles, then it becomes unstable and emits y-rays.
8.
21. (b) : In face centred cubic structure (fee) radius
(a)
9.
(a) : As we know, E = hdX MX For « 4 greater transition, greater the energy difference, lesser will be the wavelength. 10. (b) : The well defined circular path around the nucleus in which the electron revolves is called orbit however the region in space around the nucleus, where the probability of finding electron is maximum is called orbital. 11. (a) : Mn —» [Ar] 3d5 4s2 Mn 4+ - » [Ar] 3cP 4i'Q 3d 4s 1 1
1
•
Number of unpaired electrons = 3 18
of the atom r =
a
, as the atoms touch each other
along the face diagonal of the cube. a
~ 2>/2 a (edge length) 22. ( a ) :
2 V 2 = 2V2 • /• • ^Zr = — / " . V2 V2
0.059, 1 0.059, 1 = — log?, = — 2 - l o g — 0.059
4p
(-2) = 0.059 V = 59 mV. (increase)
23. (a): In case of zero order reaction, the concentration of reactant decreases linearly with time, as its rate is independent of the concentration of the reactants. CHEMISTRY TODAY | SEPTEMBER '05 20
24. ( b ) : A°m ( c 6 h 5 c o o h ) - a 0 ( c 6 h 5 c o o - )
+ aC
30. (a) : Of all the acid derivatives, acid chlorides, i.e. CH3COCI is most reactive. The order of reactivity of acid derivatives decreases in the following order: RCOC1 > ( R C 0 ) 2 0 > RCOOR > RCONH 2 .
'(h + )
= 42 + 288.42 = 330.42 a =
1 Ay0
m
330.42
25. ( b ) : Reimer-Tiemann.reaction involves the carboncarbon bond formation. OH ONa PHD NaOH, 340 K OJ +CHCl 3
dil. HCl -NaCl
CHO salicylaldehyde
NO, 26. (b)
gives only monosubstitution NO,
product as - N 0 2 group is meta directing and only one m-position is possible in w-dinitrobenzene. 27. ( d ) : Xe is highly polar since the ionisation potential of xenon is quite close to the ionisation potential of oxygen. 28. ( a ) : Because of high electronegativity, H - F forms strong H-bonds. As a result, it exists as an associated molecule (HF)„. Thus, the boiling point (293 K) of HF is abnormally high. The boiling points of the hydrogen halides of other elements are much lower than that of H - F. However, after a sudden drop in boiling point from HF to HCl, the boiling points of other hydrogen halides gradually increase from HCl to HI because of increase in size of the halogen atom CI to I. In other words, volatility decreases in the order : HCl > HBr > HI > HF as the boiling points increase in the order: HX HCl HBr HI HF Boiling pt. 1 8 9 K 206 K 238 K 293 K 29. (d) : Relationship between mole fraction of a component in the vapour phase and total vapour pressure of an ideal solution. y
A
-
Ed _ /'total XA-Pa •
18
1x1
1x1+2x2
x
a'PA +x b ' Pb
= — = 1 = 0.2 1+4 5
31. (b) : Freezing point is the t e m p e r a t u r e at which the liquid and the solid form of the same substance are in equilibrium and hence have the same vapour pressure. Due to lower t r„ temperature vapour pressure of the solution, solid form of a solution separates out at a lower temperature as shown in figure. The decrease is called depression in freezing point. When solid is the solute, it is solvent that freezes. Hence in the given question water will be separated out first. 32. (a) : CH = CH
— — CH3CHO
OMgBr
C H
P/Br,
CH, - C - H
H
B r
•
Br
OH
CH3 - C - CH3
^
CH, - C - H CH,
CH, H i H-C I H - C ^
33. (b)
C-H II C-H
I H 12a and 3Ji-bonds 34. (d) : v m s : yl302R = =>
3 RT M 3 RT M
30x307? =
3i?x300 M
M = ^ ^ = l g6 m = 0.001 kg. 6 30x30
35. (c) : Reaction can be explained as follows. O 0 (i)
/ H
x
CH3
/ H
C
\r. CH2
enolate ion
CHEMISTRY TODAY | SEPTEMBER'0522
a 7s
O II
o
A=R CH,
(ii)
H O II
A
H
OCH,
CH.
r
CH 2 - C - OCHJ
45. (b): With calculated amount of Grignard reagent, acetyl chloride forms ketones. CI CH3COCI + J f M g C H , > CH3COCH3 + M g \ X
-OCH,-
CH,
O "
A 1 1
H
O
CH2-C-CH3
(5-ketoaldehyde
36. (d) : Both are mirror images of each-other, I and II are identical. 37. (a) : Aim : C 2 H 6 + 7/2 0 2 -> 2C0 2 + 3H 2 0 AH = [2 A///(C0 2 ) + 3AHf (H 2 0)] - [AHf (C2H6) + 7/2 AHf(02)] = [2 (-94.1) + 3(-68.3)] - [-21 + 0] = - 3 7 2 kcal. 2a
38. (a) : *f 2 X 39. (a) : A + 2 5 ZfM
=
i
.
dt
M
5xl(T
^
m
68
1
i - H2 n — • 69 y -
172 69
C+D 4
= 2.5x10- mol"' sec"'.
2 dt 2 40. (c): N 2 : KK a ( 2 s f a*(2s)1 n(2px)2 n(2py)2 a(2p.)2 (diamagnetic) 2 2 2 C2 : KK o(2s) a*(2s) n(2px) n(2py)2 (diamagnetic) N2+ : KK CT(2s)2 a*(2s)2 n(2px)2 n(2py)2 a(2pz)1 (paramagnetic) 0 2 2 " : KK a(2s)2 a*(2s)2 a(2pz)2 n(2px)2 n(2py)2 n*(2px)2 n*(2py)2 (diamagnetic) 41. (a) : CH3COOH + NaHC0 3 -> CH 3 COONa + C 0 2 + H 2 0 42. (b) : C2H5CHO
CHjMgBr H+/H2O
H
L
C22 H5 5 - C - O H I CH,
C*-chiral carbon as all the four valencies are attached with different substituents or groups. 43. (a) : Sucrose is a disaccharides which upon acid or enzymatic hydrolysis gives only two molecules of monosaccharides. „ H+ or invertase ^ „ , , , Sucrose > D (+)-glucose + D (-) -fructose 44. (a) : Anhydride of nitrous acid is N 2 0 3 . CHEMISTRY TODAY | SEPTEMBER '05
46. (a) : As A reacts with hydroxylamine it means A may be aldehyde or ketone. But it does not react with Fehling solution hence A must be a ketone. Secondly it forms iodoform which is a characteristic reaction of methyl ketone. NOH O II NH,OH CH3C — CH2CH2CH3 CH 3 C-CH 2 CH 2 CH 3 I 2 /NaOH
' CHI, OH
I
H,0
CH3 — C — CH 2 CH 2 CH 3 4
CI I CHj(p — CH0CH7CH3
CI (4) 47. (a) : In order to make the image permanent, it is necessary to remove the unreduced silver bromide from the surface of the developed film. This operation is called fixing of image. Fixing is done by dipping the developed film or plate in sodium thiosulphate (hypo) solution. The hypo solution dissolves the unreduced silver bromide by forming a complex. AgBr + 2Na 2 S 2 0 3 Na 3 [Ag(S 2 0 3 ) 2 ] + NaBr OH
sodium argentothiosulphate (soluble)
Thus sodium thiosulphate acts as a complexing agent. 48. (a) : < ^ 0 ) - N t c r + H - ^ ) - OH
< 0 > -
N = N
base..
- < 0 > - O H
/)-hydroxy azobenzene (orange dye)
This is an example of coupling reaction. 49. (d) : In S 2 0 7 2 - ion, the two S atoms are linked through an oxygen atom forming one S - O - S bond. Each sulphur atom is further connected to three oxygen atoms (forming two S O and one S - O - bonds). Thus, there is no S - S bond. But in all other ions there is a S - S bond. 50. (c) : Penicillinis not a broad spectrum antibiotic since it is active against infections caused by gram positive bacteria only. 23
SOLVED PAPER
J a m m u & K a s h m i r CET - 2 0 0 5 1. Who used the quantum theory for the first time to explain the structure of atom? (a) de Broglie (b) Bohr (c) Heisenberg (d) Einstein. 2. The boiling point because (a) the atmospheric (b) the temperature (c) the atmospheric (d) the temperature 3. and is (a) (c)
of water decreases at high altitudes pressure is low is low pressure is high is high.
In a solid lattice, the cation has left a lattice site is located at interstitial position, the lattice defect interstitial defect Frenkel defect
(b) vacancy defect (d) Schottky defect.
4. The entropy of crystalline substances at absolute zero going by the third law of thermodynamics should be taken as (a) 100 (b) 50 (c) zero (d) different for different substances.
(a) acetic acid (c) ethanol
(b) glucose (d) urea.
10. The unit ohm - 1 is used for (a) molar conductivity (b) equivalent conductivity (c) specific conductivity (d) conductivity. 11. The tendency of an electrode to lose electrons is known as (a) electrode potential (b) reduction potential (c) oxidation potential (d) e.m.f. 12. For the feasibility of a redox reaction in a cell, the e.m.f. should be (a) positive (b) fixed (c) zero (d) negative. 13. If the rate of reaction A B doubles on increasing the concentration of A by 4 times, the order of the reaction is (a) 2 (b) 1 (c) 1/2 (d) 4. 14. Fog is a colloidal solution of (a) solid in gas (b) liquid in gas (c) gas in liquid (d) gas in solid.
AG for a spontaneous reaction is zero (b) negative positive could be positive or negative.
15. Muddy water can be purified through coagulation using (a) common salt (b) alums (c) sand (d) lime.
6. The IUPAC name for CH 3 CO - CH 3 is (a) dimethyl ketone (b) acetone (c) propanal (d) propanone.
16. Formation of ammonia from H 2 and N 2 by Haber's process using Fe is an example of (a) heterogeneous catalysis (b) homogeneous catalysis (c) enzyme catalysis (d) non-catalytic process.
5. (a) (c) (d)
7. Which of the following is not an endothermic reaction? (a) dehydrogenation (b) ethane to ethene (c) combustion of propane (d) change of chlorine molecule into chlorine atoms. 8. A process in which the system does not exchange heat with the surroundings is known as (a) isothermal (b) isobaric (c) isochoric (d) adiabatic. 9. 34
Which of the following is not a non-electrolyte?
17. The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by 10°C is (a) the value of threshold energy increases (b) collision frequency increases (c) the fraction of the molecule having energy equal to threshold energy or more increases (d) activation energy decreases. CHEMISTRY TODAY
SEPTEMBER '05
18. The pH of an aqueous solution having hydroxide ion concentration as 1 x IO-5 is (a) 5 (b) 9 (c) 4.5 (d) 11. 19. Which of the following is not a Lewis acid? (a) BF3 (b) A1C13 (c) HCl (d) LiAlH 4 . 20. The precipitation takes place only when the product of concentrations of ions (a) exceeds the solubility product (b) is less than the solubility product (c) is negligible (d) is equal to the solubility products. 21. Which of the following has lowest electron affinity? (a) CI (b) 1 (c) F (d) Br.
29. The presence of the chlorine atom on benzene ring makes the second substituent enter at a position (a) ortho (b) meta (c) para (d) ortho/para. 30. Hydrogen is not obtained when zinc reacts with (a) cold water (b) hot NaOH solution (c) conc. sulphuric acid (d) dilute HCl. 31. The oxidation number of xenon in XeOF 2 is (a) zero (b) 2 (c) 4 (d) 3. 32. Which of the following is most volatile? (a) HF (b) HCl (c) HBr (d) HI. 33. The form of iron having the highest carbon content is (a) cast iron (b) wrought iron (c) strain steel (d) mild steel.
22. In the calcium fluoride structure the co-ordination number of the cation and anions are respectively (a) 6, 6 (b) 8, 4 (c) 4, 4 (d) 4, 8
34. Which belongs to the actinides series? (a) Ce (b) Cf (c) Ca (d) Cs.
23. The total number of orbitals possible for principal quantum number n is (a) n (b) rr (c) In (d) 2rr.
35. Which of the following is planar? (a) XeF2 (b) Xe0 3 F (c) Xe0 2 F 2 (d) XeF 4 .
24. The pair having similar geometry is (a) PCI3, NH 3 (b) BeCL, H 2 0 (c) CH 4 , CC14 (d) IFS, PF 5 .
36. Cr0 3 dissolves in aqueous NaOH to give (a) Cr0 4 2 (b) Cr(OH) 3 (c) Cr 2 0 7 2 " (d) Cr(OH),.
25. The (/-orbital involved in sp3d hybridisation is (b) dxy
37. Which of the following is a tribasic acid? (a) H 3 P0 4 (b) H 4 P 2 0 7
(d) dxx.
(c) H 4 P 2 0 7
(a) rf 2 _ (c) d_2
2
26. If 8.0 g of a radioactive substance has a half-life of 10 hrs., the half life of 2.0 g of the same substance is (a) 2.6 hr (b) 5 hr (c) 10 hr (d) 40 hr. 27. (a) (b) (c)
Loss of a beta particle is equivalent to increase of one neutron only decrease of one neutron only both (i) and (ii) (d) none of these.
28. Which of the following is incorrect? (a) Relative lowering of vapour pressure is independent of the nature of the solute and the solvent. (b) The vapour pressure is a colligative property. (c) Vapour pressure of a solution is lower than the vapour pressure of the solvent. (d) The relative lowering of vapour pressure is directly proportional to the original pressure. 18 CHEMISTRY TODAY | SEPTEMBER '05
(d) H 4 P 2 O 6 .
38. The total number of possible isomers for the complex compound [Cu n (NH 3 ) 4 ][Pt"Cl 4 ] are (a) 3 (b) 6 (c) 5 (d) 4. 39. The molecule having a pyramidal shape out of the following is (a) CO, (b) PC13 (c) SF 4 (d) NH 3 . 40. Which of the following doesn't give a ppt. with silver nitrate solution? (a) ethyl bromide (b) sodium bromide (c) calcium chloride (d) sodium chloride. 41. Which is the most stable carbocation? (a) wo-propyl cation (b) triphenylmethyl cation (c) ethyl cation (d) «-propyl cation. 42. Which is most acidic of the following? (a) methane (b) acetylene (c) 1-butene (d) neo-pentane. 35
18 43. Which is most reactive of the following? (a) ethyl acetate (b) acetic anhydride (c) acetamide (d) acetyl chloride. 44. Which of the following will be chiral? (a) CH3CHC12 (b) CH 3 CHBrCl 2 (c) CD2C12 (d) CH 2 ClBr. 45. Electronic configuration of deuterium atom is (a) Is 1 (b) 2s 2 (c) 2s 1 (d) Is2. 46. Which of the following is a phenol? (a) pentanoic acid (b) phthalic acid (c) picric acid (d) phosphoric acid. 47. Which of the following is not an organometallic compound? (a) C 2 H 5 ONa (b) CH 3 MgI (c) tetraethyl tin (d) KC4Hc,. 48. The correct order of electron affinity is (a) B < C < O > N (b) B > C > N > O (c) O > C > B > N (d) O < C < B < N. 49. ZieglerNatta catalyst is an organometallic compound containing (a) iron (b) titanium (c) rhodium (d) zirconium. 50. Which of the following cannot undergo nucleophilic substitution under ordinary conditions? (a) chlorobenzene (b) /er/-butylchloride (c) isopropyl chloride (d) none of these. 51. The compound which contains all the four 1°, 2°, 3° and 4° carbon atoms is (a) 2,3-dimethyI pentane (b) 3-chloro-2,3-dimethylpentane (c) 2,3,4-trimethylpentane (d) 3,3-dimethylpentane. 52. Brass, bronze and german silver have one metal in common. This is (a) Zn (b) Fe (c) A1 (d) Cu. 53. Which of the following is the green coloured powder produced when ammonium dichromate is used in fire works? (a) Cr (b) Cr0 3 (c) Cr 2 0 3 (d) Cr0(0 2 ). 54. The 7t-bonded organo metallic compound which has ethene as one of its component is
(a) Zeise's salt (b) ferrocene (c) dibenzene chromium (d) tetraethyl tin. 55. Malachite is an ore of (a) Fe (b) Ag (c) Cr
(d) Cu.
56. The most acidic of the following is (a) ClCH 2 COOH (b) C 6 H 5 COOH (c) CD 3 COOH (d) CH 3 CH 2 COOH. 57. Which of the following is an electrophile? (a) H 2 0 (b) S0 3 (c) NH 3 (d) ROR. 58. An aromatic compound among other things should have a 7T-electron cloud containing (4n + 2)ji electrons where n can't be (a) 1/2 (b) 3 (c) 2 (d) 1. 59. Glycerol is an alcohol which can be classified as (a) trihydric (b) monohydric (c) dihydric (d) hexahydric. 60. The oxidation number of cobalt in K[Co(CO) 4 ] is (a) +1 (b) +3 (c) - 1 (d) - 3 . 61. Bromination of alkanes involves (a) carbanions (b) carbocations (c) .carbenes (d) free radicals. 62. (a) (b) (c) (d)
Methylphenyl ether can be obtained by reacting phenolate ions and methyl iodide methoxide ions and bromobenzene methanol and phenol bromo benzene and methyl bromide.
63. (a) (b) (c) (d)
Which is not correct? Phenol is more acidic than acetic acid. Ethanol is less acidic than phenol. Ethanol has lower boiling point than ethane. Ethyne is a non-linear molecule.
64. Ascorbic acid is also known as (a) vitamin A (b) vitamin B (c) vitamin C (d) vitamin D. 65. Reaction of phenol with chloroform/sodium hydroxide to give o-hydroxy benzaldehyde involves the formation of (a) dichloro carbene (b) trichloro carbene (c) chlorine atoms (d) chlorine molecules. 66. One of the following that cannot undergo dehydrohalogenation is CHEMISTRY TODAY | SEPTEMBER '05 36
(a) iso-propyl bromide (c) ethyl bromide
(b) ethanol (d) none of these.
67. Which requires catalyst? (a) S + 0 2 S02 (b) 2 S 0 2 + 0 2 (c) C + 0 2 -> C 0 2 (d) all of these.
2S03
68. Acetic acid will be obtained on oxidation of (a) ethanol (b) propanal (c) methanal (d) glyoxal. 69. A carboxylic acid is converted into its anhydride using (a) thionyl chloride (b) sulphur chloride (c) sulphuric acid (d) phosphorus pentoxide. 70. (a) (b) (c) (d)
Which is false? Glucose is a disaccharide. Starch is a polysaccharide. Glucose and fructose are not anomers. Invert sugar consists of glucose and fructose.
71. What kind of isomerism is possible for 1-chloro2-nitroethene? (a) functional group isomerism (b) position isomerism (c) E/Z isomerism (d) optical isomerism. 72. KCN reacts readily to give a cyanide with (a) ethyl alcohol (b) ethyl bromide (c) bromobenzene (d) chlorobenzene. 73. Peptides are formed from (a) aliphatic amines (b) carbohydrates (c) a-amino acids (d) aromatic amines. 74. Calcium carbide on reaction with water yields (a) methane (b) ethane (c) ethene (d) ethyne. 75. The correct set of the four quantum numbers of a 4d electron is (a) 4, 2, 1 , - 1 / 2 (b) 4, 2, 1 , 0 (c) 4, 3, 2, +1/2 (d) 4, 3, - 2 , +1/2. ANSWERS 1. (b) : To overcome the objections of Rutherford's model and to explain the hydrogen spectrum, Bohr proposed a quantum mechanical model of the atom, which is based on the quantum theory of radiation and the classical laws of physics. 2.
( a ) : The normal boiling point is the temperature
18 CHEMISTRY TODAY | SEPTEMBER '05
at which the vapour pressure of a liquid is equal to exactly one standard atmospheric pressure (760 mm of Hg). Thus, at high altitudes where the atmospheric pressure is less than 760 mm, water boils at temperatures below its normal boiling point of 100°C. 3. (c) : Frenkel defect is caused if some of the ions of the lattice occupy interstitial sites leaving a corresponding number of normal lattice sites vacant. 4. (c) : According to third law of thermodynamics, "every substance has a finite positive entropy but at the absolute zero temperature the entropy may become zero and does so become in the case of perfectly crystalline solids". 5. ( b ) : The free energy of a reaction is the chemical analogue of potential energy of mechanical systems. A body moves in the direction in which there is a decrease in potential energy. Similarly, in a chemical system, the substance moves in a direction in which there is decrease in free energy, i.e. AG is negative. In a chemical reaction, AG = G producls - G reactants . Thus spontaneous changes occur with a decrease in free energy, i.e. AG is negative. 6.
(d) : CH3-CO-CH3
Ketones are named by adding the suffix '-one' in place o f ' - e ' of alkane. Thus I.U.P.A.C. name is propanone. 7. ( c ) : The enthalpy of combustion i.e. AH is always negative. It means combustion is an exothermic reaction. 8. (d): If a process is carried out under such condition that no exchange of heat takes place between the systems and surroundings, the process is termed adiabatic. The system is thermally isolated, i.e. dQ = 0 and the temperature of the system varies. 9. (a): The substances whose aqueous solutions allow the passage of electric current and are chemically decomposed, are termed electrolytes. Electrolytic substances are classified as strong or weak according to how readily they dissociate into conducting ions. Acetic acid is a weak electrolyte. Glucose, ethanol and urea are non-electrolytes. 10. (d) : Conductance = — r resistance = 4 - = o h m " or mho ohm 11. (c) : The magnitude of the electrode potential of a metal is a measure of its relative tendency to lose or 37
gain electrons, i.e. it is a measure of the relative tendency to undergo oxidation (loss of electrons) or reduction (gain of electrons). M —» M"+ + ne~ (oxidation potential) M"+ + ne~ —> M (reduction potential) 12. (a): Any redox reaction would occur spontaneously if the free energy change (AG) is negative. AG° = - nFE° where n is the number of electrons involved, F is the value of Faraday and E° is the cell emf. AG° can be negative if E° is positive. 13. (c) : On increasing the concentration of reactant by 4 times, rate of reaction doubles, i.e. order = 1/2. 14. (b) : Fog is an example of aerosol where the dispersed phase is liquid and dispersion medium is gas. 15. (b): Alum is added to muddy water so as to destroy the bacteria as well as to coagulate the suspended impurities.
F -3.6
EA (eV)
CI -3.8
Br -3.5
I -3.2
22. (b): The Ca2+ ions are arranged in (ccp) arrangement, i.e. Ca 2+ ions are present at all corners and at the centre of each face of the cube. The fluoride ions occupy all the tetrahedral sites. This is 8 : 4 arrangement i.e, each Ca2+ ion is surrounded by 8 F~ ions and each F~ ion by four Ca 2+ ions. 23. (b) : Total number of orbitals in a principal or main energy shell is equal to n2. 24. (a, c) : PC13, NH 3 pyramidal CH 4 , CC14 tetrahedral 25. (a) : dsp3 or sp3d : one s + three p + one d (da) 26. (c) : Half-life period is defined as the time during which half the amount of a given sample of the radioactive substance disintegrates. This time period does not depend upon the initial amount of the radioactive substance.
16. (a) : The catalytic process in which the reactants and the catalyst are in different phases is known as heterogenous catalysis. N20t) + 3 H 2 t e ) - ^ - * 2 N H 3 t e ) The reactants are in gaseous state while the catalyst is in solid state.
27. (b): Loss of beta particle is equivalent to decrease of one neutron only. n —> p + e~ + v
17. (b): When the temperature is increased, heat energy is supplied which increases the kinetic energy of the reacting molecules. This will increase the number of collisions and ultimately the rate of reaction will be enhanced.
29. (d): Chlorine atom is ortho-para directing group.
18. (b) : [OH"] = 1 x 10"5 pOH = - log[OH"] = 5 pH + pOH = 1 4 => pH = 14 - 5 = 9. 19. (d) : LiAlH 4 is a nucleophilic and capable of donating electron pair, thus acts as a Lewis base. 20. ( a ) : When the ionic product exceeds the solubility product, the equilibrium shifts towards left hand side, i.e. increasing the concentration of undissociated molecules of the electrolyte. As the solvent can hold a fixed amount of electrolyte at a definite temperature, the excess of the electrolyte is thrown out from the solution as precipitate. Thus, for the precipitation of an electrolyte, it is necessary that the ionic product must exceed its solubility product. 21. (b) : In a group, electron affinity decreases as the size increases. 18
28. (d) : According to Raoult's law, the relative lowering in vapour pressure of a dilute solution is equal to mole fraction of the solute present in the solution. 30. (c) Zn Zn Zn
: Zn + H 2 0 ZnO + H 2 + 2NaOH Na 2 Zn0 2 + H 2 + 2HC1 - > ZnCl 2 + H2 + 2H 2 S0 4 ZnS0 4 + S0 2 + 2H 2 0.
31. (c) : Suppose the oxidation state of Xe is x. XeOF 2 x + (-2) + 2(—1) = 0 =» x - 2 — 2 = 0 => JC - 4 = 0 => x = +4. 32. ( d ) : The bond strength H - X decreases from HF to HI. Thus, HF is most stable while HI is least stable. The decrease in stability is due to decrease in electronegativity from F to I. This is also observed in the values of dissociation energy of H - X bond. H - F H - CI H - Br H - I Dissociation energy
136
105
86
70
(kcal mol" 1 )
HF and HCl are stable upto 1200°C, HBr dissociates slightly and HI dissociates considerably (20%) at 440°C. 33. (a) : Cast iron : iron - 93-95% carbon - 2.5-5%, impurities about 2%.
CHEMISTRY TODAY | SEPTEMBER '05 38
34. (b) : Ce - lanthanide, Cs - alkali metal, Cf - actinide, Ca - alkaline earth metal. 35. (d) : In the formation of XeF4, sp2cP hybridisation occurs which gives t h e molecule an octahedral structure. The xenon and four fluorine atoms are coplanar while the two equatorial positions are occupied by the two lone pairs of electrons. 36. (a) : Cr0 3 + 2NaOH
RCOC1 > ( R C 0 ) 2 0 > RCOOR' > RCONH 2 In other words, the reactivity decreases as the basicity of the leaving group increases i.e. C P < RCOCT < R O - < N H 2 -
^
Na 2 Cr0 4 + H 2 0 yellow solution
37. (a) : H 3 P0 4 ^ H + + H 2 P0 4 H2PO4~ ^ H + + HP0 4 2 " HP0 4 2 " ^ H + + P0 4 3 " H 3 P0 4 is a tribasic acid due to presence of three replaceable hydrogen atoms. 38. (d) 39. ( b ) : In PC13, P atom undergoes sp3 hybridisation. In the tetrahedral configuration, one of the position is occupied by a lone pair. Thus it is pyramidal in shape. 40. (a) : It doesn't provide free Br" ions to react with AgN0 3 . 41. (b) : Stability of carbonium ions: tertiary alky 1 > secondary alkyl > primary alkyl > methyl. More the number of alkyl groups, the greater the dispersal of positive charge and therefore, more the stability of carbonium ion is observed.
CH 3
U 44. (b) : Br - C — CI
* asymmetric or chiral carbon
H
All the four valencies of carbon are satisfied with different atoms/substituents. 45. (a) : Atomic number of deuterium = 1 ]D2 W 46. (c) : Picric acid is 2,4,6-trinitrophenol. 47. ( a ) : C 2 H 5 ONa is not an organometallic compound as there is no carbon-carbon metal bond. 48. (a) : As we go from B —¥ C —¥ O, EA increases due to decreasing size and increasing nuclear charge. The EA of N is however, zero because of the extra stability of the exactly half-filled 2p orbitals. Thus, the overall sequence is B < C < O > N. 49. (b) : A Zeigler-Natta catalyst is composed of at least two parts: a transition metal component and a main group metal alkyl compound. The transition metal component is usually either titanium or vanadium. The main group metal alkyl compound is usually an aluminium alkyl. 50. (d) : All the given species undergo nucleophilic substitution reaction. This reactivity can be explained in terms of the nature of C - X bond which is highly polarised covalent bond due to large difference in the electronegativities of carbon and halogen atoms. 8+
8-
-C-X
triphenylmethyl cation Dispersal of positive charge increases with the increase in the number of benzene ring. 42. (b) : The s-character of C - H bond of acetylene is higher in comparison to C - H bond of ethene and ethane. The electrons of the C - H bond in acetylene are strongly held by carbon nuclei. This facilitates the removal of hydrogen as proton. 43. (d) : The order of reactivity of acid derivatives towards different reactions decreases in the order: 18 CHEMISTRY TODAY | SEPTEMBER '05
1=
'"CH, 'CH 3
I
3
I
2°
1°
51. (b) : C H 3 - C H - C - C H , - C H , 30
4o|
CI 3-chloro-2,3-dimethylpentane 52. (d) : Brass - Cu = 60-80%, Zn = 40-20% Bronze - Cu = 75-90%, Sn = 25-10% German silver - Cu = 56%, Zn = 24%, Ni = 20% Common metal is copper. 53. (c): (NH 4 ) 2 Cr 2 0 7
2K 2 Cr0 4 + Cr 2 0 3 + 1 0 2 39
o,
Ka
10-5 > IO"7 > IO"10 > 1 0 - 1 4 RCOOH H 2 C0 3 C 6 H s OH HOH HO
J 0-18
ROH
Fe
K
64. (c) :
54. (a) : ferrocene
18
Ascorbic acid (vitamin C)
65. (a) : This is Reimer-Tiemann reaction where the electrophile is dichlorocarbene (: CC12) generated from chloroform by the action of a base. OH" + CHC13 — HOH + : C C l f —> CI" + : CC12
(C2H5)4Sn
66. (b): Ethanol cannot undergo dehydrohalogenation.
tetraethyl tin
67. (b) : The reaction 2 S 0 2 + 0 2 2 S 0 3 requires V , 0 5 or platinised asbestos as a catalyst in contact process. [O] 68. (a) : C 2 H 5 OH > CH,COOH
dibenzene chromium
55. (d) : Malachite : CuC0 3 -Cu(0H),_ 56. ( a ) : Any electron withdrawing substituent (having -I-effect) stabilises the anion by dispersing the negative charge and therefore, increases the acidity. Chlorine is an electron withdrawing group. 57. (b) : H - O - H , :NH3 , R - O - R - nucleophiles S0 3 has electron deficient centre (a reagent which can accept an electron pair in a reaction, is called an electrophile). 58. (a) : According to Huckel rule, all aromatic compounds must have (4n + 2)n electrons where n is an integer, i.e. n = 0, 1, 2, 3,... and possesses unusual stability due to the complete delocalisation ofm-electrons. 59. (a) : Glycerol (CH 2 OH - CHOH - CH 2 OH) is a trihydric alcohol, which may be considered as derivative of propane, obtained by replacement of three hydrogen atoms from different carbon atoms by three hydroxyl groups.
RCO
RCOOH
/ O +H20 RCOOH RCO' P 2 0 5 acts as a dehydrating agent. 69. (d) :
- >
70. ( a ) : Glucose is a monosaccharide having chemical composition C 6 H 1 2 0 6 . 71. (c) : 0 2 N H C = CHC1 1 -chloro-2-nitroethene
For highly substituted alkenes E and Z system of nomenclature is used which is based on a priority system developed by Cahn, Ingold and Prelog. alcohol
72. (b) : C 2 H 5 Br + KCN
>
C 2 H 5 CN + KBr
73. (c) : Peptides are formed by condensation of a-amino acids. H 2 N-CH,COOH + H 2 N - C H 2 - C 0 0 H
H2N - CH, - C O M ! - CH2COOH peptide bond
60. (c) : Let the oxidation number of Co is x. 1 + x + 0 = 0 => x = -l.
V
61. (d): Halogenation of alkanes takes place in presence of light (sunlight or UV) or at elevated temperature via free radical.
and so on. 74. (d) : CaC 2 + H , 0 C 2 H 2 + Ca(OH) 2 .
62. (a) : C 6 H 5 0" + C 2 H 5 I
75. (a) :
C 6 H 5 OC 2 H 5 + I"
63. (a) : Phenols are much more acidic than alcohols but less so than carboxylic acids or even carbonic acid. This is indicated by the values of ionisation constants. The relative acidity follows the order:
ethyne
J = ±
; n = 4, / = 2, m = - 2 , - 1 , 0, +1, +2
I
> ±
2
I, 2
+
I,±i 2'
2
j ±
I
2
Questions sent by : Mohd. Abass Padder, Anantnag, J & K
CHEMISTRY TODAY | SEPTEMBER '05 40
SOLVED PAPER
BIHAR C EC E (MAINS 1. One mole each of H 2 0 , CO, H 2 and C 0 2 are mixed in a 10 litre flask and heated to 1476 K. 20% of water reacts with CO according to the equation: H 2 O w + C O w / H 2 (G) + C O , Calculate the equilibrium constant of the reaction. 2. What is the per cent dissociation of acetic acid in a solution of 0.5 M acetic acid and 0.1 N HCl? [Ka for CH 3 COOH is 1.8 x 10"5]. 3. 1.355 g of a substance dissolved in 55 g of CH3COOH produced a depression in the freezing point of 0.618°C. Calculate the molecular weight of the substance. [K,= 3.85], 4. How long has a current of 3 amperes to be passed through a solution of silver nitrate to coat a metal surface of 80 cm 2 with a 0.005 mm thick layer? Density of Ag is 10.5 g cm" 3 . Atomic weight of Ag = 108. 5. (a) (c) (e)
Name the following complex salts: K 2 [Ni(CN) 4 ] (b) [Co(NH 3 ) 3 (NO,) 3 ] [Pt(NH 3 ) 6 ]Cl 4 (d) [Cr(H,0) 3 (NH 3 ) 3 ]Cl 3 Ni(CO) 4 .
6. On the basis of MO theory, explain why: (a) bond order of 0 2 + is greater than that of O, (b) He 2 + is paramagnetic in nature 7. A 0.62 g . s a m p l e of N a 2 C 0 3 - H 2 0 is added to 100 ml of 0.1 N H,S0 4 . Will the resulting solution be acidic, basic or neutral? [At. weight of Na = 23, S = 32], 8. (a) (b) (c) (d) (e)
Write balanced equation for the following. P4 + concentrated H N 0 3 —> K M n 0 4 + H 2 0 , (in acidic medium) —> A1 + NaOH (aqueous) —> Zn + dilute H N 0 3 H 2 S 0 4 + HI - »
CC14 H 2 0 (k), C 0 2 (j;) and HCl fe) are - 2 5 . 5 , - 5 7 . 8 , -94.1 and -22.1 kcal/mole respectively. Calculate AH°29S for the reaction CC14 + 2 H 2 0 w - » CO, fe) + 4HC1 (K). 11. Complete the following equations: (a) Phenol (b)
(C,H5),S04
B e n z o i c acid
9
->9
HCN, HCl
'
NaOH >
PhNHNH, ^
A1C1,
C6HsCOCl
NH
9
?
12. An unknown compound with molecular formula C 5 H l 0 O does not reduce Fehling's solution but forms a bisulphite addition compound. It gives a positive iodoform test. What are its possible structures? 13. Electromagnetic radiation of X = 242 nm is just sufficient to ionize Na atom. Calculate the ionization energy of Na atom in kJ/mole. c = 3 x 108 ms" 1 , h = 6.626 x IO"34 Js. 14. 0.50 g of an organic compound in Kjeldahl's method gave NH 3 , which was absorbed in 50 ml of 1 N H 2 S0 4 . The neutralisation of remaining acid required 60 ml of 0.5 N NaOH. Find the % N in the compound. 15. (a) (c) (e)
Give the name of the monomers of the following, Natural rubber (b) Polypropylene Teflon (d) Neoprene Plexiglass.
16. Write chemical equations for (a) Leaching of bauxite to obtain A1 2 0 3 . (b) Roasting of copper pyrites to obtain C u 2 0 . 17. ^ T h disintegrates to give
Pb . How many a
and P particles are emitted?
9. The reaction 2 N , 0 5 —» 4 N 0 2 + 0 2 is carried out at constant volume. The concentration o f N 0 2 increases by 1.6 x 10 -2 mole in 4 seconds. Calculate the rate of appearance of O,.
18. Classify the following as Lewis acids and Lewis bases. (a) CH 3 NH, (b) CN" (c) AICI3 (d) Fe 3+ (e) CO,.
10. The standard heats of formation at 298 K for
19. Convert (in two steps only).
36
CHEMISTRY TODAY | OCTOBER '05
(a) (b) (c) (d) (e)
Methane to ethane Ethane to ethylene Acetylene to acetaldehyde Acetylene to but-2-yne. Acetic acid to methane.
(b) [Co(NH 3 ) 3 (N0 2 ) 3 ] t r i a m m i n e t r i n i t r o cobalt(III)
(c) [Pt(NH 3 ) 6 ]Cl 4 Hexa ammineplatinum(IV) chloride
(d) [Cr(H 2 0) 3 (NH 3 ) 3 ]Cl 3
20. The ionization constant of NH 4 + in water is 5.6 x 10"10. The rate constant for the reaction of NH 4 + and OH" to form NH 3 and H 2 0 is 3.4 x IO10 I mol"1 sec"1. Calculate the rate constant for proton transfer from H 2 0 to NH 3 . [KW = 10 1 4 ]. SOLUTIONS 1.
H 2 0 ( , ) + CO ( g )
Initial c o n c . At eqm.
2.
1
—
1
(1 - 0.2)
(1 - 0.2)
1.2X1.2
[H20][C0]
0.8x0.8
0.5
0.1
1
_
2
,
+
C 0
2 (g)
1
x H + + Cl" 0.1
0
0
x
x
5
=L8x10
_5
x < < < 1, the value of x can be negligible. = •
^
0 2 + : KK (o2s)2 (a*2s) 2 (o2Px)2 (n2Py)2 (n2p,)2
Na 2 C0 3 + H 2 S0 4
1.8x10~ 5 x 0.5 _ g x j Q-S 5
10
10
0
0
0
Meq. left
0
0
10
10
10
3
N,Na,S0 4
10
100
= 0.1
1000 x K j - x w
S o l u t i o n b e c o m e s neutral s i n c e b o t h acid a n d b a s e are used up
WxA T 1000x3.85xl.355 = 153.47 55x0.618
and N a 2 S 0 4 d o e s n o t s h o w h y d r o l y s i s .
4.
Mass of silver to be deposited = volume x density = area x thickness x density = 80 x 0.0005 x 10.5 = 0.42 g. Applying to silver, £ = Z * 96500. 108
Z=g 96500 W = Z-i-t
i.e. 0.42 =
108 x 3 xt 96500
96500x0.42 t== 125.09 seconds = 2.08 minutes. 108x3 5.
Na2S04 + H , 0 + C02
Meq. added
% dissociation = 9 x 10" x 100 = 9 x 10" . 3.
~ 2
Due to presence of one unpaired electron, He 2 + is paramagnetic in nature. 0.62 x1000 = 10 7. Meq. of N a 2 C 0 3 H 2 0 62 Meq. of H 2 S0 4 = 100 x 0.1 = 10
= 1.8x10-* 0.1
(n*2Py?
=l =
2
(0.5-x)
•
(a) 0 2 : KK (ct2.v)2 ( g * 2 s f ( o 2 p x f ( n 2 P y f (n2Pzf (n*2p y Y (71*2/7,)' 8-4 4 „ B . O = — = r 2 6.
Bond order of 0 2 + is greater due to absence of one electron in antibonding molecular orbital. (b) He 2 + : o ( l s ) 2 a * (Is) 1 B.O. = 2 - 1 _ 1
0.1
x0c + 0T)
Tetracarbonylnickel(O)
(1 + 0.2)
^ CH 3 COO" + H+
CH 3 COOH HCl
(g)
2
(1 + 0.2)
[H2][CQ2]
0.5 -
H
Triamminetriaquochromium(III) chloride
(e) Ni(CO) 4
(a) K 2 [Ni(CN) 4 ] potassium tetracyanonickelate(II)
CHEMISTRY T O D A Y | OCTOBER '05
8.
(a) P 4 + conc. H N 0 3 [2HN0 3 -> H 2 0 + 2 N 0 2 + O] x IO P4 + 100 + 6H 2 Q 4H 3 PQ 4
P4 + 20HN0 3 4H 3 P0 4 + 2 0 N 0 2 + 4 H 2 0 (b) K M n 0 4 + H 2 0 2 (in acidic medium) —> 2KMn0 4 + 3H 2 S0 4 K 2 S0 4 + 2MnS0 4 + 3 H , 0 + 5 0 5H 2 Q 2 + 5 0 -> 5H 2 Q + 5Q 2 2KMn0 4 + 3H 2 S0 4 + 5H 2 0 2 A K 2 S0 4 + 2 M n S 0 4 + 8H20 + 502 (c) A1 + NaOH (aqueous) —> 2A1 + 2NaOH + 2H,0 -> 2NaA10,2 + 3H, T 2 I I2 sodium meta-
solution
aluminate
37
f (d) Zn + dilute H N 0 3 Zinc reacts with very dilute nitric acid (6%) to form ammonium nitrate. [Zn + 2 H N 0 3 Zn(N0 3 ) 2 + 2H] x 4 H N 0 3 + 8H NH 3 + 3 H , 0 NH 3 + HNQ 3 -> NH 4 NQ 3 4Zn + 10HN0 3 4Zn(N0 3 ) 2 + N H 4 N 0 3 + 3H z O very dilute Zn reacts with dilute H N 0 3 (20%) to form nitrous oxide (N 2 0). [Zn + 2 H N 0 3 Zn(N0 3 ) 2 + 2H] x 4 2HNQ 3 + 8H - » N 2 Q + 5H 2 Q 4Zn + 10HN0 3 4Zn(N0 3 ) 2 + N 2 0 + 5 H 2 0 dilute (e) H 2 S 0 4 + HI H 2 SQ 4 + 2HI -> SP 2 + I 2 + 2H 2 Q 9.
2N205 -> 4N02 + 0 2 1 4N2Q5] 1 d[ NQ 2 ] d[ o 2 ] Rate = —— : =— ; = : 2 dt 4 dt dt
AH
f (C02) +
4AH
(a) CH3CCH2CH2CH3 + NaHSO. CH3V .OH /C< CH3CH2CH2 S0 3 Na O II (b) CH3CCH2CH2CH3 + Ag 2 0 — > no reaction O II (c) CH3CCH2CH2CH3 + 3I2 + NaOH > CHI 3 + CH 3 CH 2 CH 2 COONa Hence the given compound is pentanone-2.
E = ho-
hc _ 6.626X10" 34 X3X10 ;
X 242 xlO" 9 = 0.082 x IO""17 J = 0.082 x IO"20 kJ. Energy per mole for ionisation
d[ P 2 ] = rate of reaction = 1 x 10 3 mol. litre 'sec dt AH°=AH f' (products)
CH3CCH2CH0CH3 O
13. X = 242 nm = 242 x 10~9 m c = 3 x 108 ms"1
= 0.1x10" Rate = —x4 4 = l x ] 0~3 mol litre -1 sec" 1 . Rate of appearance of 0 2 :
10.
ketone. It undergoes iodoform test, means it must be a methylketone. O
-AH,' (reactants)
° f (HO)] - [ ^ f (CC14) +
(H20)
= [-94.1 + 4(-22.1)] - [-25.5 + 2(-57.8)] = - 9 4 . 1 - 88.4 + 25.5 + 115.6 = - 1 8 2 . 5 + 141.1 = - 4 1 . 4 kcal.
= 0 . 0 8 2 x i o - 2 0 x 6 . 0 2 x 10 23
= 493.6 kJ mol-'. 14. Mass of organic compound = 0.50 g Unused acid required = 60 ml of N/2 NaOH 60 ml N/2 NaOH = 60'ml N/2 H 2 S 0 4 = 30 ml N H 2 S 0 4 Acid used for absorption of ammonia = (50 - 30) = 20 ml N H 2 S 0 4 0/ f -t 1.4 x TV] x F 1.4x1x20 % of nitrogen = ttt =— = 36%. W 0.50 15. (a) Natural rubber :
(C 2 H 5 ) 2 SO„
HCN, H C l .
NaOH
A1C1,
CH33 I CH,= C H - C = C H 2
Monomer - isoprene
2-methyl-1,3 -butad iene
(b) Polypropylene :
CH3 — CH — CH,
Monomer - propylene CH=NH (b) C6H5COOH
CHO C6H5C0C1
CH—NNHPh c 6 H 5 CONH,
12. Compound C 5 H 1 0 O forms a bisulphite addition compound. It means it has a carbonyl group. As it does not reduce Fehling's solution i.e., it is a -'38
propene-1
(c) Teflon: Monomer - tetrafluoroethene CF2 = CF2 (d) Neoprene : Monomer - chloroprene
CI I C H 2 = CH - C = CH2
CHEMISTRY TODAY | OCTOBER '05
(e) Plexiglass : Monomer - methylmethylacrylate
(c) Acetylene to acetaldehyde CH = CH + 2CH 3 C00H
CH, I 3
Hg
" > CH3CH(OOCCH3)2
acetylene
ethylidene acetate
CH2=C-COOCH3 16. (a) Bauxite ore contains ferric oxide, titanium oxide and silica as impurities. When the powdered ore is digested with an aqueous solution of sodium hydroxide at about 150°C under pressure, the alumina dissolves forming soluble sodium meta-aluminate while ferric oxide (Fe 2 0 3 ), Ti0 2 and silica remain as insoluble part. A1 2 0 3 + 2NaOH -> 2NaA10 2 + H 2 0 NaA10 2 + 2 H 2 0 Al(OH) 3 + NaOH ignited
2Al(OH)3
autoclave
17.
Pb Decrease in mass = 234 - 206 28 Mass of a-particle = 4 So number of a-particles emitted = 28/4 = 7 N u m b e r of (J-particles emitted = 2 x number of a-particles - (at. no. of p a r e n t - a t . no. of end product) = 2 * 7 - (90 - 82) = 14 - 8 = 6.
19. (a) Methane to ethane
methane
CI,
CH3C1
uv
Wurtz reaction h e a t w i t h N a in e t h e r
CH,3 - CH,3 ethane
(b) Ethane to ethylene CH,3 - CH,3 ethane
to)
CH = CH
CH,CH,Br
alc K 0 H
-
-'38 C H E M I S T R Y T O D A Y | OCTOBER '05
2CH,I
2Na
NaC = CNa •
liq. N H .
CH3C — CCH3 but-2-yne
(e) Acetic acid to methane Na0H
CH3COOH
> CH3COONa
> CH,2= CH.2 ethylene
CH4 methane
,10 20. NH 3 + H 2 0 ^ = ^ N H 4 + O H " \ K h = 3.4x10 Kh NH 4 OH + H + ; Ka = 5.6x10
NHj + H20
-10
K
f
K
(base)NH3 (^•acid
x
Kf 3.4x10
^c.d(NH:)
Kh
-^base
=
^w)
IO"14 m=
5.6x10
io.
Kff = 6.07 x 1 0 s Questions sent by : Pooja Singh
CHEMISTRY TODAY
HOW TO CONTACT US
18. CH 3 NH 2 - Lewis base (due to presence of lone pair of electrons) CN _ - Lewis acid (due to electron deficient nature) A1C13 - Lewis acid (due to electron deficient nature) Fe 3+ - Lewis acid (due to electron deficient nature) C 0 2 - Lewis acid (due to presence of a multiple bond between atoms of dissimilar electronegativity)
CH 4
CH 3 CO-
acetic acid
206 82
T , l h
CH3CO s ^ _ O
(d) Acetylene to but-2-yne
A1203 + 3H 2 0
(b) The concentrated ore is heated strongly in a current of air on the hearth of the reverberatory furnace. During roasting the following changes take place. (i) S + 0 2 -> S 0 2 (ii) 4As + 3 0 2 2As 2 0 3 4Sb + 3 0 2 2Sb 2 0 3 (iii) 2CuFeS 2 + 0 2 Cu 2 S + 2FeS + S 0 2 (iv) 2FeS + 3 0 2 -> 2FeO + 2 S 0 2 2Cu 2 S + 3 0 2 2Cu20 + 2S02 234 90
>CH3CHO+
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Very Similar MODEL TEST PAPER for
CBSE-AIEEE 2 0 0 6
Time : 4 hrs.
Maximum Marks : 675
Instructions: 1. This question paper contains 225 questions: 1-75 Physics, 76-150 Chemistry, 151-225 Mathematics 2. For every correct answer 3 marks will be credited to your account, 1 mark will be deducted for every wrong answer and no marks will be awarded for unattempted questions. 3. Use of Trigonometric table, Calculator or any other helping device is restricted. 4. Useful data : At.wt./ Mol.wt. : K M n 0 4 : 158; Cu : 63.5; NaOH : 40; HCl : 36.5; Mg : 24; H : 1; He : 4; C : 12; N : 14; O : 16; Na : 23; P : 31; S : 32; CI : 35.5; Ca : 40; Zn : 65; Ag : 108. Atomic No : H : 1; He : 2; Li : 3; Be : 4; B : 5, C : 6; N : 7; O : 8; F : 9; Na : 11; Mg : 12; A1 : 13; Si : 14; Fe : 26; Co : 27; Ni : 28; Cu : 29; Zn : 30; Rb : 37 C o n s t a n t s : g = 10 m/s 2 , R = 8.3 J K - ' m o H or 0 . 0 8 2 1 atm litre K ' m o l - ' , e = 1.6 x 1 0 " " C, N„ = 6 . 0 2 3 * 10 2 3 , mp = 1.6 x 10 -27 kg, me = 9.11 * 10"31 kg, h - 6.6 x IO"34 Js.
PHYSICS 1. (a) (c)
The dimensions of permittivity (e0) of vacuum are M-'L-3T4I2 (b) ML"3T2I2 3 4 2 M"'L T I (d) ML3T2I2
2. IfP represents radiation pressure, C represents speed of light and Q represents radiation energy striking a unit area per second, then the non-zero integers x,y and z such that PxQyCz is dimensionless are (a) x= ],y= \,z= 1 (b) * = 1, y = -1, z = 1 (c) x = -l,y= 1 , 2 = 1 (d) x = l,y= l , z = - l . 3. Which of the following displacement-time (x - t) graphs shown in figure cannot possibly represent onedimensional motion of a particle?
a parachutist bails out from it. After 3 s he opens his parachute and decelerates at a constant rate of 5 ms"J. What was the height of the parachutist above the ground when he opened his parachute? Talce g = 10 ms~2. (a) 15 m (b) 30 m (c) 45 m (d) 60 m. 5. In vector diagram shown in figure, R is the rpsultapt of vectors A and 5 . If tf = B/Jl, the value of angle 9 is (a) 30° (b) 45° (c) 60° 6. (a) (b) (c) (d)
B
/
90°r
A
(d)
75°.
A null vector has zero magnitude and a specific direction a finite magnitude and no specific direction a finite magnitude and no specific direction zero magnitude and no specific direction.
7. The maximum height attained by a projectile is increased by 10% by changing the angle of projection, without changing the speed of projection. The percentage increase in the time of flight will be (a) 20% (b) 15% (c) 10% (d) 5%. 8. A car, moving at a speed of 54 km h~', is to go round a curved road of radius 30 m. If the curved road is not 18
CHEMISTRY TODAY | SEPTEMBER '05 14
banked, what must be the coefficient of friction between the tyres and the road for the car to negotiate the curve? Take g = 10 ms~2. (a) zero (b) 0.25 (c) 0.50 (d) 0.75 9. Two masses m and 2m are joined to each other by means of a frictionless pulley as shown in figure. When the mass 2m is released, the mass m will ascend with an acceleration of (a) g/3 (b) g/2
r
\
F=2mg (C)
g
(d) 2g.
10. A block of mass M is lying on a horizontal frictionless surface. One end of a rope mass m is fixed to the block and a force F is applied at the free end parallel to the surface. The force acting on the block will be FM (a) F (b) (M + m) Fm Fm (d) (M - m) (c) (M + m) 11. An engine pulls a car of mass 1500 kg on a level road at a constant speed of 5 ms~'. If the frictional force is 500 N, what power does the engine generate? (a) 5.0 kW (b) 7.5 kW (c) 10 kW (d) 12.5 kW. 12. A particle of mass 0.1 kg is subjected to a force which varies F (N) with distance as shown in figure. If it starts its journey x(m) from rest at x = 0, its velocity at x = 12 m is (a) zero (b) 20V2 m/s (c) 20^3 m/s (d) 40 m/s.
•
13. A shell explodes into three fragments of equal masses. Two fragments fly off at right angles to each other with speeds of 9 ms -1 and 12 ms -1 . What is the speed of the third fragment? (a) 9 ms"1 (b) 12 ms"1 1 (c) 15 ms" (d) 18 ms-1. 14. A rubber ball is dropped from a height of 5 m on a -'38 CHEMISTRY TODAY | OCTOBER '05
planet where the acceleration due to gravity is not known. On bouncing it rises to 1.8 m. The ball loses its velocity on bouncing a factor of (a) 16/25 (b) 2/5 (c) 3/5 (d) 9/2. 15. A circular disc is rolling down an inclined plane without slipping. If the angle of inclination is 30°, the acceleration of the disc down the inclined plane is (a) g (b) g/2 V2 (d) (c) g/3 T g. 16. A thin uniform metallic triangular sheet of mass A/has sides AB = BC - L. What is its moment of inertia about axis AC lying in the plane of the sheet? (a)
(b) (d) 17. 1%, (a) (c)
MU_ 12 Ml}
IK jv
Axis of rotation
i l k , C'*I (c)
ML
2ML If both the mass and the radius of earth decrease by the value of the acceleration due to gravity will decrease by 1% (b) increase by 1% increase by 2% (d) remain unchanged.
18. A satellite of mass m is orbiting the earth at a height h from its surface. If M is the mass of the earth and R its radius, the kinetic energy of the satellite is GmM „ GmM (a) 7~ . (b) (R + hy 2(R+hy GmM GmM (d) 2 (R + h) (c) (.R + h) 19. The normal density of gold is p and its bulk modulus is K. The increase in density of a lump of gold when a pressure P is applied uniformly on all sides is (a) pP/K (b) pK/P (c) P/pK (d) K/pP. 20. A steel wire of cross-sectional area 3 x 10"6 m2 can withstand a maximum strain of 10"3. Young's modulus of steel is 2 x i o " Nm~2. The maximum mass of the wire can hold is (take g = 10 ms -2 ). (a) 40 kg (b) 60 kg (c) 80 kg (d) 100 kg.
21. A cube of ice is floating in a liquid of relative density 1.25 contained in a beaker. When the ice melts, the level of the liquid in the beaker (a) rises (b) falls (c) remains unchanged (d) falls at first and then rises to the same height as before. 22. Two blocks A and B are made of different kinds of wood. Block A floats in water with ] /4th of its above the surface of water. Block B floats in water with 2/3 rds of its volume below the surface of water. The ratio of densities of A and B is (a) 3 : 2 (b) 5 : 3 (c) 9 : 8 (d) 4 : 3. 23. Which one of the graphs shown in figure represents the velocity-time (v-t) graph of a small spherical body falling in a viscous fluid?
(a)
1:2
(b)
(c)
1 : 2V2
(d)
1 : V2 2V2
28. An ambulance blowing a siren of frequency 700 Hz is travelling slowly towards a vertical reflecting wall with a speed of 2 ms~'. The speed of sound is 350 ms -1 . How many beats are heard per second? (a) 4 (b) 6 (c) 8 (d) 10. 29. When a metallic bar is heated from 0°C to 100°C, its length increases by 0.05%. What is the coefficient of linear expansion of the metal? (a) 5 x IO"3 °C~' (b) 5 x IO"4 °Cr[ 5 (c) 5 x 10" °C-' (d) 5 x IO"6 °C-'. 30. When a solid metallic sphere is heated, the largest percentage increase occurs in its (a) diameter (b) surface area (c) volume (d) density. 31. The temperature coefficient of resistance of the material of a wire is 0.00125 per°C. Its resistance at 300 K is 1 ohm. At what temperature will the resistance of the wire be 2 ohm? (a) 1154 K (b) HOOK (c) 400 K (d) 1127 K.
24. Two spheres of equal masses but radii R and 2R are allowed to fall in a liquid. The ratio of their terminal velocities is (a) 1 : 4 (b) 1 : 2 (c) 1 : 32 (d) 2 : 1. -'38 25. A spring of force constant k is cut into three equal pieces. If these three pieces are connected in parallel, the force constant of the combination will be (a) k/3 (b) k/9 (c) 3k (d) 9k.
32. Cooking vegetables and other food in a pressure cooker saves time and fuel because (a) under increased pressure, water can be made to boil at a temperature much higher than 100°C (b) under increased pressure, water can be made to boil at a temperature much lower than 100°C (c) heat losses are reduced to a minimum (d) condensation of steam is prevented.
26. A small spherical steel ball is placed a little away from the centre of a large concave mirror of radius of curvature R = 2.5 m. The ball is then released. What is the time period of the motion? Neglect friction and take g = 10 ms -2 . (a) n/4 sec (b) jt/2 sec (c) 7t sec (d) 2n sec
33. Figure shows the P-V A diagram for a Camot cycle. In this diagram represents (a) curve AB isothermal process and BC • adiabatic process represents (b) curve AB adiabatic process and BC. isothermal process (c) curves CD and DA represent isothermal process (d) curves CD and DA represent adiabatic process.
27. Transverse waves of the same frequency are generated in two steel wires A and B. The diameter of A is twice that of B and the tension in A is half that in B. The ratio of velocities of waves in A and B is
34. One mole of a monoatomic gas (y = 5/3) is mixed with one mole of a diatomic gas (y = 7/5). What will be the value of y for the mixture? (a) 1.5 (b) 1.54 (c) 1.4 (d) 1.45 CHEMISTRY TODAY | OCTOBER '05
35. If a gas .has / degrees of freedom, the ratio of C / C v of the gas is (a)
1+ /
(c)
(b)
l+ {
(d)
1+
/
42. The plates of a parallel plate capacitor are charged to 100 V. A 2 mm thick plate is inserted between the plates. Then to maintain the same potential difference, the distance between the capacitor plates is increased by 1.6 mm. The dielectric constant of the plate is (a) 5 (b) 1.25 (c) 4 (d) 2.5
36. A vessel contains a mixture of 1 mole of oxygen and two moles of nitrogen at 300 K. The ratio of the rotational kinetic energy per 0 2 molecule to that per N 2 molecule is (a) 1 : 1 (b) 1 : 2 (c) 2 : 1 (d) depends on the moment of inertia of the two molecules.
43. Three resistances of 4 Q each are connected as shown in figure. If the point D divides the resistance into two equal halves, the resistance between points A and D will be (a) 12 Q (b) 6 Q (c)
37. If the temperature of a black body increases from 7°C to 287°C, then the rate of energy radiation increases by
44. A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities that remains/remain constant along the length of the conductor is/are (a) current, electric field and drift speed (b) drift speed only (c) current and drift speed (d) current only.
(a) (c)
4
(b)
16
(d)
2.
38. A black body is at a temperature of 2880 K. The energy of radiation emitted by this body between wavelengths 499 nm and 500 nrn is V\, between 999 nm and 1000 nm i s / A and between 1499 nm and 1500 nm is U3. The Wien's constant b = 2.88 x 106 nm K. Then (a) ( 7 , = 0 (b) U3 = 0 (c) U\ > U2 (d) U2>U]. 39. Three point charges 4q, Q and q are placed in a straight line of length / at points distant 0, //2 and I respectively. The net force on charge q is zero. The value of Q is (a)
-q
(b) - 2 q
40. A metallic solid sphere is placed in a uniform electric field. In figure, which path will the lines of force follow? (a) 1 (b) 2 (C)
3
3 Q
(d) 1/3 Q.
A constant voltage is applied between the two ends uniform metallic wire. Some heat is developed in it. heat developed is doubled if both the length and radius of the wire are halved both the length and radius of the wire are doubled the radius of the wire is doubled the length of the wire is doubled.
(d) 4q.
46. A battery of emf E and internal resistance r is connected across a pure resistive device (such as an electric heater) of resistance R. The power output of the device will be maximum if (a) R = r (b) R = j2r (c) R = 2r (d) R = 4 r.
(d) 4.
47. A conducting circular loop of radius r carries a constant i. It is placed in a uniform magnetic field B such that B is perpendicular to the plane of the loop. The magnetic force acting on the loop is (a) irB (b) 2 nirB (c) zero (d) nirB.
41. If n drops, each of capacitance C and charged to a potential V, coalesce to form a big drop, the ratio of the energy stored in the big drop to that in each small drop will be (a) n : 1 (b) n m : 1 ,5/3 . | Ml -2 1. (c) n (d) -'38 CHEMISTRY TODAY | OCTOBER '05
45. of a The (a) (b) (c) (d)
4a
48. A current I flows along the length of an infinitely long, straight, thin walled pipe. Then (a) the magnetic field at all points inside the pipe is the same but not zero
(b) (c) (d)
the magnetic field at any point inside the pipe is zero the magnetic field is zero only on the axis of the pipe the magnetic field is different at different points inside the pipe.
49. A rectangular loop of sides 8 cm and 2 cm having resistance of 1.6 £2 is placed in a magnetic field of 0.3 T directed normal to the loop. The magnetic field is gradually reduced at the rate of 0.02 T s -1 . How much power is dissipated by the loop as heat? (a) 1.6 x 10"10 W (b) 3 . 2 x l O - , 0 W -10 (c) 6.4 x io W (d) 12.8 x 10~'° W. " F i g u r e ^ c d n shows two coils 0000000000 w m r n s P and Q placed 0 p close to each L p t L other. When the circuit of coil P is suddenly broken by lifting the key K, (a) a current flows from X to Y in coil O (b) a current flows from Y to X in coil Q (c) no current flows in coil Q (d) an alternating current flows in coil Q.
3600 waves pass through a point in a medium in 2 minutes, its wavelength is (a)
13.8 m (b) 25.3 m
(c)
41.5 m
(d) 57.2 m.
55. No photoelectrons are emitted from a metal if the wavelength of light exceeds 6000 A. The work function of the metal is approximately equal to (a) 3 x 10- ,s J (b) 3 x 10"19 J 20 (c) 3 x IO" J (d) 3 x 10-22 J. 56. Which energy state of doubly ionized lithium (Li^) has the same energy as that of the ground state of hydrogen? Given Z for lithium is 3. (a) n = 1 (b) n = 2 (c) n = 3 (d) n = 4.
50
51. A convex lens is placed between an object and a screen which are fixed distance apart. For one position of the lens the magnification of the image obtained on the screen is mv When the lens is moved by a distance d, the magnification of the image obtained on the same screen is m2. The focal length of the lens is (m] > m2) d ^
(0
(
m
]
,m\
- m
d 2
)
(
b
)
(d)
{mx +m2) d-
52. Monochromatic light is refracted from air into glass of refractive index The ratio of the wavelengths of the incident and refracted wave is (a) 1 : 1 (b) 1 : (X (c) \ i : 1 (d) tf : 1. 53. In Young's double slit experiment the distance d between the slits and S2 is 1.0 mm. What should the width of each slit be so as to obtain 10 maxima of the two slit interference pattern within the central maximum of the single slit diffraction pattern? (a) 0.1 mm (b) 0.2 mm (c) 0.3 mm (d) 0.4 mm. 54. The speed of a wave in a medium is 760 ms -1 . If -'38
57. Choose the wrong statement. A thermonuclear fusion reactor is better than a fission reactor for the following reasons: (a) for the same mass of substances involved, a fusion reaction releases much more energy than a fission reaction (b) a fusion reaction can be much more easily controlled than a fission reaction (c) a fusion reaction produces almost no radioactive waste (d) the fuel required for fusion is readily available in abundance from sea-water. 58. The radioactivity of an old sample of whisky due to tritium (half-life 12.5 years) was found to be only about 3% of that measured in a recently purchased bottle marked '7 years old'. The sample must have been prepared about (a) 70 years ago (b) 220 years ago (c) 420 years ago (d) 300 years ago. 59. hole (a) (b) (c) (d)
If nc and nh respectively represent the electron and concentrations in a semiconductor, then it is an n-type semiconductor if «,, >> nh a p-type semiconductor if ne < < nh a pure semiconductor if ne = nh a good conductor if nc = nh.
60. In figure the input is across the terminals A and C and the output is across B and D. Then the output is (a) zero (b) the same as the input (c) full wave rectified (d) half wave rectified. CHEMISTRY TODAY | OCTOBER '05
61. Starting with the same initial conditions, an ideal gas expands from volume F, to F2 in three different ways. The work done by the gas is W{ if the process is purely isothermal, W2 if purely isobaric and if purely adiabatic. Then (a) W2> Wx> W.^ (b) w2 > rv3 > w, (c) Wx > W2 > W3 (d) ivl > w\ > w2 62. Eight equal resistances, each of magnitude R, are connected as shown in the figure. The resultant resistance between P and Q is (a) 4K/5 (b) 8/?/15 (c) 3/?/8 (d) 5R/Z
:R 1 \R /r^J c}
/
\
R
J
63. Periodic time of a particle executing SHM is T. 3T After a time — from equilibrium position, the ratio of potential and kinetic energies of the particle is (a) 3 : 1 (b) 1 : 3 (c) 2 : 1 (d) 1 : 2 64. The potential difference F of an electric field E = (yi + x j ) is (a) (b) (c) (d)
V = (x + y) + constant V = ( x - y ) + constant V = xy + constant F = - xy + constant
65. Time-constant of an L-R circuit is T0. A current / 0 flows through it. The source of current is switched off
f d')
at time t = 0 I I when is represented by r. Assuming this rate to be constant, the current will reduce to zero in a time interval of (a) eT0 (b) TJe (c) T0 (d) e/T, 66. Water rises to a height h in a vertical capillary tube. The tube is inclined at 60° with the vertical. Length of water column will be (a) h (b) 2h (c) h sin 60° (d) h cos 60° 67. An object is placed at 15 cm from first focus of an equiconvex lens. Real image is formed at 60 cm from second focus of the lens. The focal length of the lens is (a) 75 cm (b) 60 cm (c) 45 cm (d) 30 cm -'38 CHEMISTRY TODAY | OCTOBER '05
68. In a compound microscope fo= 1.5 cm and fe = 2.5 cm. Length of tube = 25 cm. The magnifying power when final image is formed at infinity is approximately equal to (a) 25 (b) 60 (c) 110 (d) 140 69. that will (a) (c)
A particle is projected from earth's surface such it escapes. Total mechanical energy of the particle be infinite (b) positive finite negative finite (d) zero
70. A person covers first half of a linear journey with velocity Vj and the second half with velocity v2. The mean v is given by v, + v.
(a) (c)
1 1 1 - =- + — V
Vj VI
v2 V-
2 (b)
1
1
+ —
= —
—
V
v
v
(d)
2
v
i ~ 2
71. The angular speed of earth at which a body lying on equator loses its weight is (Given g = 10 m/s 2 , Radius of earth = 6,400 km) (a)
1 radian 80
sec
1 radian
(c)
,,, (b) (d)
1 radian 800
sec
1
radian
40 sec 400 sec 72. An engine accepts compressed steam at 127°C and rejects it at 47°C. Efficiency of the engine is (a) 40% (b) 30% (c) 20% (d) 10% 73. The colour of bright fringe nearest to the central achromatic fringe in the interference pattern with white light will be (a) violet (b) red (c) yellow (d) green 74. The maximum speed of a particle executing SHM is 10 m/s and maximum acceleration is 31.4 m/s 2 . Its periodic time is (a) 2 s (b) 4 s (c) 6 s (d) 1 s 75. The relation between magnetic susceptibility % and absolute temperature T, for a paramagnetic material, is (a)
X~ T
(c) X
1
(b) x « V77 ^
( d )
1
CHEMISTRY 76. In a reaction, 4 mol of electrons are transferred to one mol of HN0 3 . The possible product obtained due to reduction is (a) 0.5 mol o f N 2 (b) 0.5 mol of N 2 0 (c) 1 mol of N 0 2 (d) I m o l o f N H j 77. If 0.5 mol of BaCl2 is mixed with 0.2 mol ofNa 3 P0 4 , the maximum number of mol of Ba 3 (P0 4 ) 2 that can be formed is (a) 0.7 (b) 0.5 (c) 0.2 (d) 0.1 78. 100 mL of 1 M KMn0 4 oxidised 100 mL H 2 0 2 in acidic medium. Volume of same KMn0 4 required in alkaline medium to oxidise 100 mL of H 2 0 2 will be 100 , 500 T (a) mL (b) — mL (c)
300
—
,
(d) None.
mL
79. Which combination is odd w.r.t. oxidation number per atom of the underlined? (a)
H2SOS, H 2 S 2 0 8 , K2CR207
(b) (c)
Cr0 3 , CrCr3+ + Ni2++H20 the correct coefficients of the reactants for the balanced reaction are :
2
Ni 3 3
H 14 14
(c)
1
1
16
(d)
3
3
12
Cr2Oy~ (a)
(b)
(d) none of these.
3
1
80. When 1 * 10~ mol of the chloride of an element Y was completely hydrolysed, it was found that the resulting solution required 20 ml of 0.1 M aqueous silver nitrate for complete precipitation of the chloride ion. Element Y could be (a) aluminium (b) phosphorus (c) silicon (d) sulphur.
87. 100 ml of H 2 0 2 is oxidised by 100 mL of 1M KMn0 4 in acidic medium ( M n 0 4 reduced to Mn2+) 100 mL of same H2Oz is oxidised by Fml of 1M KMn0 4 in basic medium ( M n 0 4 reduced to MnO,). Hence V is
81. [Cr(NH 3 ) 5 Br] CI and [Cr(NH 3 ) 5 Cl] Br can be distinguished by X and isomerism shown is Y. X and Y are : (a) BaCl2, ionisation (b) AgN0 3 , ionisation (c) AgN0 3 , coordinate (d) BaCl2, linkage.
88. N 2 + 3H2 —> 2NH3 Molecular weight of NH3 and N2 are x, and x 2 their equivalent weight are and y2. Then (yj -y2) is :
82. Which gives maximum number of ions due to ionisation? (a) PtCl4 • 6NH 3 (b) PtCl 4 -5NH 3 (c)
PtCl4 • 4NH 3
(d)
equal.
83. Among the following species, identify the isostructural pairs : NF3, NOJ, BF3, H 3 0 + , HN 3 (a)
[NF3, NOJ] and [BF3, H 3 0 + ]
(b)
[NF3, HN 3 ] and [NOJ, BF3]
(c)
[NF3, H 3 0 + ] and [NOJ, BF3]
(d)
[NF3, H 3 0 + ] and [HN3, BF3]
46
(a)
500
(b) 100
2X]
(a)
(c)
(3x] - x2)
(c)
100/3
(d) 500/3
(b) (x, - x2) (d) (x, - 3x2)
89. A rad ioactive element X, decays by the sequence and with half lives, given below X [half Life = 30 min] k< > Y + a Y [half Life = 20 days] — + 20 which of the following statements is correct ? (a) disintegration constant k2 > (b) atomic number of X and Z are same (c) the mass number of Y is greater than X (d) Y and Z are isotopes CHEMISTRY TODAY | OCTOBER 05
90. The radiation is emitted when a hydrogen atom goes from a high energy state to a lower energy state. The wavelength of one line in visible region of atomic spectrum of hydrogen is 6.5 x 10 _7 m. Energy difference between the two states is : (a) 3.0 x IO"19 J (b) 1 . 0 x l O " l 8 J 10 (c) 5.0 x 10~ J (d) 6.5 x 10"7 J
KC1 with 100% ionisation will be : [K f = 2.0 mol"' kg and molarity = molality] (a) 5.0° (b) 3.2° (c) 1.6° (d) 0.8°
91. In an experiment, 50 ml of 0.1 M solution of a metallic salt reacted exactly with 25 ml of 0.1 M solution of sodium sulphite. In the reaction SO 2 " is oxidised to SC>4~. If the original oxidation number of the metal in the salt was 3, what would be the new oxidation number of the metal? (a) 0 (b) 1 (c) 2 (d) 4
and half life period is 7— where ka { a - x ) is the concentration of reactant after time t, starting with 7" (sec) initial concentration a (all _i concentration in mol L ar.i.; time in second). A graph between (a - x) _1 and time 1 is of the type. If OA = 50 mof 1 L and 9 = tan 1 (0.1) then half life period is (a) 500 sec (b) 6.93 sec (c) 50 sec (d) none.
92. In centro-symmetric system, the orbital angular momentum, a measure of the momentum of a particular travelling around the nucleus, is quantised. Its magnitude is h_ (a) (b) J n r T ) _ 271
(c)
7 7 ( 7 + 1 ) Jl 2%
(d)
271
93. If n and / are respectively the principal and azimuthal quantum numbers, then the expression for calculating the total number of electrons in any energy level is
(a) (c)
94.
1 2 ( 2 / + 1)
(b)
/=1 /=//+]
I
"i" , 2(2/ + l) 1=1
/=»-1
2(2/+ 1)
1=0
/
(d)
I
/=0
2(2/+ 1)
Gas
o2
N2
NH3
CH4
a
1.360
1.390
4.170
2.253
The table indicates the values of van der Waal's constant a. (The unit of a is L2 atrn mol -2 ). The gas which can most easily be liquefied is (a) 0 2 (b) N 2 (C) NH, (d) CH4 95. Mixture of volatile components A and B has total V.P. (P = 2 5 4 - 119x) {x = mol fraction of B) Hence pA° and pls° are (a) 135,254 (b) 119,254 (c) 254,135 (d) 135,119 96. 25 mL of an aqueous solution of KC1 was found to require 20 mL of 1 M AgN0 3 solution when titrated using a K.2Cr04 as indicator. Depression in freezing point of -'38 CHEMISTRY TODAY | OCTOBER '05
97. For the second order reaction 1
rate constant k is k =
1
1
98. Rate constant of a reaction, k is 3.0 x 10-4 s_1, energy of activation E„ = 104.4 kJ mol 1 and Arrhenius constant as T —¥ °° is (a) 2.0 x 1018 s"1 (c) infinite
(b) (d)
6.0 x 1014 s~' 3.6 x io 30 s"1
99. The resulting of iron-pipe exposed to atmosphere follows the reaction, 2Fe (s) + 30 2 (g) —> Fe 2 0 3 (s). This is a (a) spontaneous reaction (b) non-spontaneous reaction (c) neither spontaneous reaction nor non-spontaneous reaction (d) may be spontaneous or non-spontaneous depending on conditions 100. The dissociation energy of CH 4 and C 2 H 6 are respectively 360 and 620 kcal/mol. The bond energy of C—C bond is (a) 260 kcal m o f (b) 180 kcal moM (c) 130 kcal mol"1 (d) 80 kcal m o l 1 s 101. Given Na (s) > Na (g), Na (g) —^ ~> Na+ (g) + e", Cl2 (g) CI (g) + e~
(a) (c)
2C1 (g)
-> cr (g),
Na+(g) + CI" (g) > NaCl (s) AHy of NaCl (s) is - U (b) S + J + D- E- U S+ 1+2D-E-U 2S + 2I + D-2(E
+ U)
102. Ky, of CaS0 4 is 4 x IO 1 2 . CaS0 4 is precipitated on mixing equal volumes of the following solutions (a) 3 x IO"6 M CaCl 2 and 3 x 10"6 M (NH 4 ), S0 4 (b) 4 x 10" 6 M CaCl 2 and 3 x IO"6 M (NH 4 ) 2 S0 4 (c) 6 x -10"6 M CaCl 2 and 3 x 10"6 M (NH 4 ) 2 S0 4 (d) In all cases. 103. pH of 0.01 M HS" will be (a)
pH = 7 +
pKu
logc
2
2
(b)
PH
= 7-
pKh
logc
pKx - pK2
(c)
pH =
(d)
PH = 7 + 2+
pKu - pKh
(d) none.
105. 100 m L o f a buffer of 1MNH 3 and 1 NH 4 are placed in two voltaic cells separately. A current of 1.5 A is passed through both cells for 20 minutes. If electrolysis of water only takes place 2 H 2 0 + 0 2 + 4e~ 40H" (RHS) 2H z O - » 4H + + 0 2 + 4e~ (LHS), then pH of the (a) L.H.S. will increase (b) R.H.S. will increase (c) both side will increase (d) both side will decrease 106. Frenkel defect is the (a) Schottky defect (b) (c) combination of a, b (d) 107. r B a C l 2 = 1 0 0 , r H 2 s o 4 conductance (BaS0 4 ) = 22 (a) 4 x 10-4 (c) 16 x 10"4
interstitial defect none of these.
= 2 5 0 , r H C 1 = 1 2 0 . Specific x 10-4. Hence /Q 7 ,(BaS0 4 ) is (b) 10-* (d) none of these.
108. In a packing of identical spheres (of radius r), the distance of 4r is equal to the length of (a) face diagonal in fee (b) face diagonal in bcc (c) body diagonal in bcc and face diagonal in fee (d) face diagonal in bcc and body diagonal in fee 109. In octahedral void and tetrahedral void, radius ratio is (in closed packing) (a) -'38
0.414 0.225
(b)
0.225 0.414
0.225 x 0.414
(d)
none.
110. pK/, of CHjCOCT ion is 9.26. pH of a solution when 0.01 M CH3COOH is neutralised 50% and at equivalent point using 0.01 M NaOH are respectively (a) 4.63, 8.22 (b) 4.74, 8.22 (c) 2.37,4.11 (d) 4.74,8.37 111. On heating colourless solid A, gas B (liquid at room temp.) and gas C are formed. A is decomposed by NaOH on heating to form gas D giving white fumes with HCl. Gas C occupies 800 ml/g at NTP. Hence A is (a) NH 4 N0 3 (b) NaNO, (c) NH4C1 (d) NH 4 N0 2 . 112. Following gives yellow ppt. on boiling with conc. HNO3 + Amm. Molybdate :
2+
104. Zn |I Zn ||Cd |Cd If Zn —> Zn 2+ + 2e~ 0.760 V Cd - > Cd 2+ + 2e~ 0.495 V and E,a = -Ercd then [Zn 2+ ]/[Cd 2+ ] is (a) 1 (b) 20 (c) 1010
(c)
(a)
AsO;
(b)
M0O4
(c)
P 0,3-
(d)
both (a) and (c).
4
113. Black residue
(a) (c)
(Mn0 2 ) + K , C 0 3 + air -» X (green) A" + CI, Y (pink). X and Y are K,Cr 2 0 7 , KMn0 4 (b) K,Mn0 4 , KMn0 4 KMn0 4 , K 2 Mn0 4 (d) none.
114. Cr0 4 ~ (yellow) changes to C r 2 0 2 - (orange) in pH = x and vice versa in pH = y.x and y can be (a) 6 , 5 (b) 6 , 8 (c) 8 , 9 (d) 7 , 7 115. The sulphur present in an organic compound is oxidised by fuming nitric acid into (a) H,S (b) SO, (c) S0 3 (d) H 2 S0 4 116. Which of the following statements are correct for all three halogens (X), CI, Br and I ? (a) they all form oxyacids that are strong acid in aqueous solution (b) they all react with hot. conc. NaOH (aq) to give X0 4 ~ ions (c) they all need to gain one electron to acquire stable configuration (d) they all form acidic hydrides. 117. 20 mL of oxygen contracts to 17 mL when subjected to silent electric discharge in an ozoniser. What further contraction would be observed if the partially ozonised oxygen is treated with oil of cinnamon (which absorbs ozone)? CHEMISTRY TODAY | OCTOBER '05
(a) (c)
(b) (d)
2 mL 6 mL
8 mL 4 mL
H2O2,KOH,A
118. Which of the following reaction(s) give (s) coloured gases? (a)
K 2 Cr 2 0 7 + KC1 + H 2 S0 4 (conc.)
(b)
N a N 0 3 + H 2 S 0 4 (conc.)
(c) (d)
A
A
>
>
A
CuS0 4 + H N 0 3 (dil.) > Electrolysis of brine using mercury cathode and graphite anode
119. For the molecule PF 4 CH 3 , which of the following structures is the most stable, considering that CH3~ is more electropositive than F ? F CH, P - F I F F
P —CH 3 I F CH, (c)
j-pr.
(d)
F ^
J P ^ ^ F
120. Which of the following changes is not realised in the laboratory? (a) Absorption of NO by alkaline sodium sulphite to form a compound (b) Combustion of metallic Mg in C 0 2 (c) Heating hydrated magnesium chloride to get the anhydrous salt (d) Displacement of chlorine from KC10 3 by iodine to form KI0 3 121. Consider the isoelectronic series K + , S2", CI" and Ca 2+ The radii of these ionic species follows the order (a) Ca 2+ > K + > CI" > S2" (b) CP > S 2 " > K + > Ca 2+ (c) S 2 " > CC > K + > Ca 2+ (d) K + > Ca 2+ > S 2 " > CI" 122. There is loss in weight when mixture of Li 2 C0 3 and Na 2 C0 3 .10H 2 0 is heated strongly. This loss is due to (a) Li 2 C0 3 (b) Na 2 C0 3 -10H 2 0 (c) both the above. (d) none of these. 123. Solute (X) is highly soluble in water. On adding conc. H 2 S0 4 , there is no reaction and a clear solution is obtained. (A) can be (a) N a N 0 3 (b)' Na 2 HP0 4 (c) KI (d) KC1 -'49 CHEMISTRY TODAY | OCTOBER '05
AgNO,
124. Green coloured solute (A) )
yellow solution (C)
-> white ppt (B) (CH3COO)2Pb CH3COOH
Yellow ppt. (D). Which is correct? A
(a) (b) (c) (d)
AgCl AgCl AgCl CrCl 3
B
C
D
KC1 KC1 CrCl 2 AgCl
Pbl 2 PbCr0 4 PbCr0 4 K 2 Cr0 4
Pbl 2 Pb 2 Cr 2 0 7 Pbl, PbCr0 4
125. Nq 12 atoms of X (g) are converted into X~ (g) by energy EX.NJ2 atoms of X (g) are converted into X~ (g) by energy E2. Hence ionisation potential and electron affinity of X (g) are 2 £ ] 2 En 2Ei 2(EX-E2) (b) (a) Nn
— E2
(c)
2E2
(d)
Nn
none of these.
126. For the elementX, student^ measured its radius as 102 nm, student B as 103 nm and C as 100 nm using same apparatus. Their teacher explained that measurements were correct by saying that recorded values by A, B, and C are (a) crystal, van der Waal and covalent radii (b) covalent, crystal and van der Waal radii (c) van der Waal, ionK .ind covalent (d) none is correct 127. Following graph shows variation of I .P. with atomic number in Ne second period (Li-Ne). Value N F of I.P. of c / Na (11) will be 0 (a) above Ne b (b) below Ne "Li but above O i i.I i i i i i i (c) below Li 7 8 9 10 11 (d) between N Z • and O.
j
128. (a) (b) (c) (d)
L/
Following triads have approximately equal size. Na+, Mg2+, A F (isoelectronic) F", Ne, 02~ (isoelectronic) Fe, Co, Ni Mn+, Fe2+, Cr (isoelectronic).
129. Match list I with list II and select the correct answer
using the codes given below the lists. List I List II (manufacturing process) (catalyst used) A. Deacon's process for 1. Finely divided iron with chlorine molybdenum as promoter B. Hydrogenation of 2. Copper(II) chloride vegetable oils C. Ostwald's process 3. Finely divided nickel for nitric acid powder D. Haber's process for 4. Platinum gauze, ammonia Codes: (a) A-4, B-l, C-3, D-2 (b) A-2, B-3, C-l, D-4 (c) A-l, B-4, C-2, D-3 (d) A-2, B-3, C-4, D-l. 130. 1 mole of a substance (X) was treated with an excess of water. 2 moles of readily combustible gas were produced along with solution which when reacted with C0 2 gas produced a white turbidity. The substance (X) could be (a) Ca (b) CaH2 (c) Ca(OH)2 (d) Ca(NO,) r O
O
131. CH3 - C - CH2 - C - OCH2CH3 (D* is catalyst). A is
(a)
OH
O
I
II
A.
I
II
CH3-C = CH-C-OC2H5
(d)
formation of A is not possible.
after rotation of (a) 60° (b) 120°
(b)
(c)
-'38
240°
(d) 360°
CH2 =
(a)
CH2N2
(b)
(c)
: CH2
(d) None of these.
C =
O
136. Which is/are less acidic than phenol? (a)
(b) \O/~0H
CH3OH
CH,
( O h OH
(c)
( d ) H 2 0.
137. Dehydration of the following in increasing order is OH
II
0 ,3/ H 2, 0
^ — O H
III
I < II < III < IV I
A
ether 1
(a) A is a mixture of CH3I and (CH3)3C - OH (b) S is a mixture of CH3OH and (CH3)3C - I. (c) A and B are identical mixture of CH 3 I and (CH3)3C - OH (d) both a & b
v
V/° 149. H - C . H-C 3 O- H 8X0U (C - O) bond lengths designated by a , (3, y and 5 are in order (a) a = y < P = 5 (b) a < ( 3 < y = 5 (c) a < y = 5 < (3 (d) all are equal.
OCH, 150.
O
NaNH,
-Br
product A by reaction R •
NH ' e l ' m i n a t ' o n addition
(a) (c)
OCH3 (b)
(d)
(a)
O
0 5
(b) (d)
1 3.
158. Consider an infinite GP with first term a and common ratio r. Its sum is 4 and the second term is 3/4, then:
, elimination addition OCH3
(c)
1001010.0011 1001100.0101.
^157, I f f ( a ) = 2, f'(a) = 1; g(a) = -1, g'(a) = 2, then value of lim g ( x ) f ( a ) - f ( x ) g ( a ) x- a
A and R are OCH, (a)
156. 74.1875 in binary is (a) 10010010.0011 (b) (5)^1001010.0101 (d)
, cine substitution
2,
none of these.
3
(b)
a = 2,r = ~ r= -
1
a= j , r = j
(d) y / = 3 , r = 4-
,. f l + 5x2 159. The value of I'm , , , *->o\. 1 + 3x
MATHEMATICS (151yA square and a parallelogram have equal bases an3 equal areas. If the perimeter of the parallelogram
(a) £
(c) cos 0
- sin 0
sin0
cos©
-1
(d) 0.
is - j times the perimeter of the square, then one angle
160. If A =
of the parallelogram must be (a) 30° (b) (c) 60° (d)
statements is not correct (a) A is orthogonal matrix (b) A' is orthogonal matrix (c) determinant A = 1 (d) A is not invertible.
45° 62° 30'.
152. Perpendiculars are drawn on the sides of an equilateral triangle from any point within the triangle, if the lengths of these p e r p e n d i c u l a r s be 6 cm, 7 cm, 9 cm, then the length of a side of the triangle is (a)
cm
(c)
22 p; — V 3 cm
(h) (b) (d)
cm
153'. If the lengths of the parallel sides of an isosceles trapezium are 20 cm and 30 cm and its area is 100 cm 2 , then the length of the non-parallel side is (a) 41 cm (b) 9 cm (c) V 4 I c m (d) 3 cm. 154. (1101101), is (a) 81 (b) 121
(c)
109
161. If a * b * c, one value of x which satisfies the 0 equation
(d) 92.
x+a x+b
(a) (c)
l l V J cm
then which of the following
x =a x =c
x-a 0 x+c
x-b x —c • • . is given by 0 (b) x = b (d) x = 0.
162. The probability that at least one of the events A and B occurs is 0.6. If A and B occur simultaneously with probability 0.2, then P(A)+ P(B) is (a) 0.4 (b) 0.8 (c) 1.2 (d) 1.4 163. I f f { x ) = x + 2 then / ' ( / ( x ) ) at x = 4 is (a) 8 \j>f 1 (c) 4 (d) 5.
155. Volume of the parallelopiped whose sides are
164. Given A = sin 2 0 + cos 4 0, then for all real value of 0
OA = 2i - 3j;
(a)
(a) (c)
52
4/13 2/7
OB = i + j-k;OC (b) (d)
= 3 i - k is 4 3/7.
(c)
3
1 then dy/dx (a) 0 (b) x (c)
\ll-x
(d)
A/tt:
220. The value of , ' ° g o " is log ah" (a) 1 + logab (b) 1 + log,a (c) 1 (d) 0. 221. If coefficients of 2nd, 3rd and 4th terms in the expansion of (1 + xy are in A.P., then value of n is (a) 2 (b) 5 (c) 7 (d) 10. 222. The inverse of the function / (x) = log I0 x is (a) KP (b) JC10 (c) e'° (d) e*. 223. If a 2 , b2, c2 are in A.P., then a b c -, , , r are in b+c c+a a+b (a) A.P. '(b) G.P. (c) H.P. (d) none of these. 224. Which is not the solution of sin79 + sin28 + sin9 = 0 (a) 0 (b) 7t/9 (c) 71/4 (d) 7i/2. 225. If 2tana + cot(3 = tan(3, then find the value of tan(P - a). (a) tana (b) cota (c) cotp (d) tanp.
( A I I M S
) F C B S E
) ( P P M F )
( A F M C
) F V M M C )
(EAMCET)
(WB-JEEI
( B H U
) ( C M C
)
2006 Medical Entrance Exam ( U P
C P M T H
(CET Karnataka
•
(MP P M t ) ( M G I M S )
Practice Test Paper l A i t t U A B i S t f U i i S A B f l [PMDT B i h a r ) (PMT HaryanjT) ( K e r a l a
1. Which element is a gas at 25°C and 1 atm pressure? (a) chlorine (b) phosphorus (c) silicon (d) sulphur 2. Which combustion product is produced the least by gasoline-powered vehicles? (a) C 0 2 (b) H 2 0 (c) N 0 2 (d) S 0 2
PMT
) (Raj.
(Manipai
i
PMT)
( JIPMER
P M T )
(T N P C E E
)
of the NaOH solution had been added. What is the concentration of the NaOH? (a) 0.07617 M (b) 0.1447 M (c) 0.1524 M (d) 0.3047 M
8. A sample Mass of evacuated flask 124.46 g of oxygen gas Mass of flask and a sample 125.10 g + oxygen of an 3. Which element has the highest electrical conductivity unknown gas Mass of flask 125.34 g at room temperature? are weighed + unknown gas (a) Ge (b) Se separately in (c) Sn (d) Te the same evacuated flask. Use the data given to find 4. H o w should a student prepare 100 ml of a the molar mass of the unknown gas (assume experiments are carried out at the same pressure and temperature), 1.0 M H 2 S 0 4 solution from a 10 MH 2 S0 4 solution? (a) 22 g/mol (b) 38 g/mol (a) Add 90 mL of H 2 0 to 10 mL of 10 MH 2 S0 4 (c) 44 g/mol (d) 84 g/mol (b) Add 10 mL of 10 M H 2 S 0 4 to 90 mL of H z O (c) Add 10 mL of 10 M H 2 S 0 4 to 80 mL of H 2 0, stir 9. Which pair of gases has the same average rate of and dilute to 100 mL after allowing to cool diffusion at 25°C ? (d) Add 80 mL of H 2 0 lOmL of 10 MH 2 S0 4 , stir and (a) He and Ne (b) N 2 and 0 2 dilute to 100 mL after allowing to cool. (c) N 0 and C 0 (d) NH and HCl
6. Mg(OH) 2 in the form of Molar Mass (g/mol) Milk of Magnesia is used to Mg(OH) 2 58.33 neutralize excess stomach acid. How many moles of stomach acid can be neutralized by 1.00 g of Mg(OH) 2 ? (a) 0.0171 (b) 0.0343 (c) 0.686 (d) 1.25 7. A 25.00 mL sample of 0.1050 M H 2 S 0 4 is titrated with a NaOH solution of unknown concentration. The phenolphthalein endpoint was reached when 17.23 mL -'38
10. According to the phase diagram shown, in what state does the represented substance exist at 1.0 atm and 0.0°C? (a) solid only (b) liquid only (c) gas only (d) solid and liquid only
M b
3
b
2
P/atm
2
5. What volume of liquid A Density (g/cm 3 ) has the same mass as 80.0 cm 3 Liquid A 0.660 of liquid B? Liquid B 3 1.59 (a) 40.0 cm 3 (b) 97.0 cm (c) 160 cm 3 (d) 193 cm 3
i 1 5 10 T/°C
11. Which liquid has the highest vapour pressure at 25°C? (a) butane, C 4 H 10 (b) glycerol, C 3 H 5 (OH) 3 (c) octane, C 8 H 18 (d) propanol, C 3 H 7 OH 12. Which oxide has the highest melting point? (a) H 2 0 (b) N 0 2 (c) S 0 2 (d) S i 0 2 13. The enthalpy change of which reaction corresponds to AFF°F for Na 2 C0 3 (s) at 298 K? CHEMISTRY T O D A Y | OCTOBER '05
(a) (b) (c) (d)
2Na (s) + C(s) + 3 / 2 0 2 (g) Na 2 C0 3 (s) N a 2 0 (s) + C0 2 (g) Na 2 C0 3 (s) 2Na + (aq) + C0 3 2 " (aq) Na 2 C0 3 (s) 2Na + (aq) + 2 0 H " (aq) + C0 2 (aq) Na 2 C0 3 (s) + H 2 0
(c) second order
(d) some other order
14. Which applies to any endothermic reaction? (a) AH < 0 (b) AH > 0 (c) AG < 0 (d) AG > 0
21. For the reaction A + B —» C, the rate law is: Rate = k[Af. Which change (s) will increase the rate of the reaction? I. Increasing the concentration of A. II. Increasing the concentration of B. (a) I only (b) II only (c) Both I and II (d) Neither I nor II
15. When a bomb calorimeter is used to determine the heat of reaction, which property of the system under investigation is most likely to remain constant? (a) number of molecules (b) pressure (c) temperature (d) volume
22. Which does NOT change with time for a first order reaction? (a) the amount of reactant that disappears in each half life (b) the concentration of the reactant (c) the length of each half-life (d) the rate of the reaction
16. For the reaction shown, AH°f (kJ-mol 1 ) which is closest to the value -143 Cr 3+ (aq) of AH? Ni 2+ (aq) -54 3 2Cr V) + 3Niw 2+ 2 C r w + 3Ni {aq) (a) 124 kJ (b) 89 kJ (c) - 89 kJ (d) - 1 2 4 kJ
23. The rates of which reactions are increased when the temperatures is raised? (a) I only (c) Both I and II
17. An distilled the ice mass of
ice cube at 0.00°C is placed in 200 g of water at 25.00°C. The final temperature after is completely melted is 5.00°C. What is the the ice cube ?
(AH/„, = 340 J• g" 1 , Cp =4.18 J-g" 1 • °C~l) (a) 23.6 g (b) 46.3 g (c) 50.0 g (d) 800 g 18. Which reaction occurs with the greatest increase in entropy? (a) 2H z O —> 2H 2 + 0 2 (g) (b) 2 N O t e ) - > N 2 0 ; ) + O 2 f e ) (c) C(s) + 02(g)^C02(g) (d) Br 2 ( p ) + C l 2 t e ) - > 2 B r C l t e ) 19. For a rate law of the form; Rate = k[A]m[Bf, the exponents m and n are obtained from (a) changes in rate with changing temperature (b) the coefficients of A and B in the balanced equation (c) the concentrations of A and B in single experiment (d) changes in the reaction rate for different concentrations of A and B. 20. What is the order of a reaction for which the units of k are L-mof'-s" 1 and the units of the rate are mol-L~' s""1? (a) zero order (b) first order -'59 CHEMISTRY T O D A Y | OCTOBER '05
I
endothermic reactions
II
exothermic reactions
(b) II only (d) Neither I nor II
24. When a catalyst is added to the system represented by this energy reaction coordinate diagram, which dimensions in the diagram are changed?
(a) 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only
(d) 1, 2, 3
25. (a) (b) (c)
Which statement is true for a reaction at equilibrium? All reaction ceases The reaction has gone to completion The rates of the forward and reverse reactions are equal. (d) The amount of product equal s the amount of reactant
26. For the hypothetical reaction, 2A (s) +B(g) ^ 3C (g) what is the equilibrium expression? [cr (a) K = [Af[B]
(c)
K =-
[C] 3 [AY + [B]
(b) K = (d) K =
3[Cj 2[A][B] [Cf [5]
27. Acetyl salicylic acid (aspirin) behaves as an acid
according to the equation shown. Calculate Kh for the C 9 H 7 0 4 - (aq) ion. (Ka = 3.0 x 10"4) HC 9 H 7 O 4 {aq) + H 2 0 / H 3 0 + ( O ? ) + C 9 H 7 0 4 ~ {aq) (a) 3.0 x 10"17 (b) 3.3 x 10"11 8 (c) 9.0 x 10~ (d) 3.3 x io 3 28. What will happen to the pH of a buffer solution when a small amount of a strong base is added? The pH will (a) increase slightly (b) decrease slightly (c) remain exactly the same (d) become 7.0 29. When a solution of NH 3 (Kh =1.8 x 10"5) is titrated with a strong acid the indicator used should change colour near a pH of (a) 1 (b) 5 (c) 9 (d) 13 30. When solid silver chloride (MM = 143.4) is added to 100 mL of H 2 0, 1.9 x 10~4 grams dissolves. What is the K,„ for silver chloride? (a) 1.3 x 10"5 (b) 3.7 x 10-6 8 (c) 3.7 x 10" (d) 1.8 x 10~10
the pressure of H 2 is 1 atm, what is E° for the halfreaction : Ga3+ iail) + 3e~ —> Ga w ? (a) - 0.54 V (b) - 0.27 V (c) 0.27 V (d) 0.54 V 36. All of the following affect the number of moles of metal deposited during electrolysis except the (a) current used (b) electrolysis time (c) charge on the ion (d) molar mass 37. The emission spectrum of hydrogen in the visible region consists of (a) a continuous band of light (b) a series of equally spaced lines (c) a series of lines that are closer at low energies (d) a series of lines that are closer at high energies 38. Which atom in its ground state has the most unpaired electrons? (a) Ge (b) As (c) Se (d) Br
31. In which species does the underlined element have an oxidation number of +2? (a) S02C12 (b) Fe(CN)64~ (c) HN0 2 (d) Ni(CO) 4
39. An monoatomic ion that has 18 electrons and a +2 charge (a) has 16 protons (b) has the symbol Ar2+ (c) has 18 neutrons (d) is isoelectronic with Ar.
32. Which transformation is an oxidation? (a) V0 3 r V0 2 + (b) Cr0 2 -> Cr0 4 2 + 2 (c) S0 3 S0 4 " (d) N0 3 - -> N 0 2 -
40. Which atom has the largest atomic radius? (a) Li (b) K (c) As (d) Br
33. _Sn 2+ (aq) + _N0 3 " (aq) + _H + (aq)
41. What is the maximum number of electrons that occupy the n = 3 level? (a) 6 (b) 8 (c) 10 (d) 18
_Sn 4+ (aq) + _NO(g) + _H 2 0 What is the coefficient for H+ (aq) when the equation above is balanced correctly with the smallest integer coefficients? (a) 2 (b) 4 (c) 6 (d) 8 34. In electrochemical cells the cathode is always the electrode where (a) oxidation occurs (b) reduction occurs (c) positive ions are formed (d) negative ions are formed 35. 2Ga w + 6H (uq) 2Ga 3+ 3H 2(g) The potential of the cell for the reaction given is 0.54 V. If the concentrations of the ions are 1.0 M and 60
42. How does the reducing ability of the elements vary across the period from Na to Ar? It (a) decreases steadily (b) increases steadily (c) decreases then increases (d) increases then decreases 43. Which species contains only covalent bonds? (a) H 2 S0 4 ' (b) NH 4 N0 3 (c) NaOCl (d) K 2 Cr0 4 44. How many valence electrons are in the pyrophosphate ion, P 2 0 7 4 "? (a) 48 (b) 52 CHEMISTRY TODAY I OCTOBER '05
(c) 54
(d) 56
45. Which species has the largest F-A-F bond angle where A is the central atom? (a) BF3 (b) CF4 (c) NF 3 (d) OF2 46. (a) (b) (c) (d)
The triple bond in carbon monoxide consists of 3 sigma bonds 2 sigma bonds and 1 pi bond 1 sigma bond and 2 pi bonds 3 pi bonds
47. The boiling points of the halogens, F2, Cl2, Br2 and I2, increase in that order. This is best attributed to differences in (a) covalent bond strengths (b) dipole forces (c) London dispersion forces (d) colligative forces 48. How many structural isomers have the formula C3H6CI2? (a) 1 (b) 2 (c) 3 (d) 4 49. A reaction in which a carboxylic acid reacts with an alcohol to form an organic compound and-water is called (a) esterification (b) hydrolysis (c) neutralization (d) saponification 50. What substance is formed when CF 2 —CF 2 is polymerized? (a) polyethylene (b) polyurethane (c) PVC (d) teflon ANSWERS 1. 6. 11. 16. 21. 26. 31. 36. 41. 46.
(a) (b) (a) (a) (a) (d) (b) (d) (d) (c)
2. 7. 12. 17. 22. 27. 32. 37. 42. 47.
(d) (d) (d) (b) (c) (b) (b) (d) (a) (c)
3. 8. 13. 18. 23. 28. 33. 38. 43. 48.
(c) (c) (a) (a) (c) (a) (d) (b) (a) (d)
-'38 CHEMISTRY TODAY | OCTOBER '05
4. 9. 14. 19. 24. 29. 34. 39. 44. 49.
(c) (c) (b) (d) (b) (b) (b) (d) (d) (a)
5. 10. 15. 20. 25. 30. 35. 40. 45. 50.
(d) (a) (d) (c) (c) (d) (a) (b) (a) (d)
tmrnm®
¥@ur
Kmmhik
Q. Is it safe to leave the aluminium lining of an old swimming pool in the ground ? A. Aluminium rapidly forms a coating of oxide when exposed to air. This is fairly unreactive but if it is exposed to moderate acid or basic conditions then it could dissolve and be mobilised in water. This aluminium could get into the local water table although it's unlikely that much if any of the aluminium would be dissolved. However, if the aluminium is in thick sheets, it is valuable - hundreds of pounds sterling per tonne possibly, so it might actually pay to get it removed. • •
•
Q. If you add just one electron to a chlorine atom, it doubles in size. Why the dramatic increase ? A. The chloride ion, CI" is larger than the chlorine atom, CI since it has one more electron but no greater nuclear charge. This is the case with all the elements in group VII of the periodic table. The radius to which the electrons extend depends on the balance of the attractive force from the nucleus and the repulsive force from all the other electrons. Probably the easiest way of thinking of this is that in a chlorine atom you have 17 protons which are equally matched by 17 electrons. When an extra electrons is added to form a chloride ion this extra electron is not counter balanced by an extra proton and so does not feel a very strong attachment to the nucleus. This makes it circulate at a much larger distance. So in the cases of the halogens, the greater radius of the anion is due to the greater electron-electron repulsion created when a further electron is added to the atom. • •
*
Q. What are the commercial uses of diatomaceous earths ? A. Diatomaceous earths are whitish, powdery silicon deposits consisting essentially of fresh water and marine plankton. They are resistant to heat and chemical reactions and are used in fireproof cements, insulating materials, as an absorbent in the manufacture of explosives and as a filter.
"Enm
PRACTICE PROBLEMS
By: Er. Arvind Tripathi (B.Tech, IT-BHU), Momentum, Gorakhpur
1. A*
(a) (c)
Ionisation constant of a weak acid (fi-4) in terms of and A m is
Ka = K„=-
rA®5
A:,(A:,-AJ
(b)
(d)
K"a
CA2
=
a:> PbS0 4 + 2Hg (/) E = 0.92 V K,„ (PbS0 4 ) = 2 x io- 8 , Kw (Hg 2 S0 4 ) = 1 x 10"6 Hence, E is (a) 0.92 V (b) 0.89 V (c) 1.04 V (b) 0.95 V
NaOH
(c)
NaOH
(d)
O
o NaOH
NaOH
8. An electron, a proton and an alpha particle have kinetic energies of 16£, 4E and E respectively.- What is the qualitative order of their de Broglie wavelengths ? (a)
K >Xp = Xa
(b)
Xp = Xa> Xe
(c)
Xp>Xe>Xa
(d)
Xa > >
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CHEMISTRY TODAY | OCTOBER '05
Very Similar MODEL TEST PAPER
for AIEEE-2006
1. The number of molecules present in a drop of water weighing 0.06 g is approximately (a) 1021 (b) 2 x 1021 21 (c) 3 x 10 (d) 4 x 1021. 2. Helium atom is two times heavier than a hydrogen molecule at 298 K, the average kinetic energy of helium is (a) two times that of a hydrogen molecule (b) same as that of a hydrogen molecule (c) four times that of a hydrogen molecule (d) half that of a hydrogen molecule. 3. and (a) (b) (c) (d)
Which of the following are the correct axial distances axial angles for rhombohedral system? a = b = c, a = P = y * 90° a = b * c, a = P = y = 90° a ± b = c, a = P = Y = 90° a * b * c\ a * P * Y * 90°.
4. To which electronic transition between Bohr orbits in hydrogen, the second line in the Balmer series belongs? (a) 3 —> 2 (b) 4 2 (c) 5 —> 2 (d) 6 —> 2. 5. In which of the following compounds does the ratio of the anion size to the cation size have the lowest value? (a) NaCl (b) KC1 (c) MgCl 2 (d) NaBr. 6. The frequency of a radiation having a wave number of 2 x 1014 cm"1 will be (a) 6.0 x 10 1 4 s-1 (b) 6.0 x 1024 s"1 3 1 (c) 6.6 x 10 s" (d) 6.6 x 10-3 s"1. 7. A molecule may be represented by three structures having energies £,, £ , and £ 3 , respectively. The energies of these structures follow the order £ 3 < £ 2 < £ , , respectively. If the experimental bond energy of the molecule is E0, the resonance energy is (a) (£, +E2 + E3) - E0 (b) E0 - £3 (c) £ 0 - £ , (d) E0-E2. -'38
8. An element {X) forms compounds of the formula XCl,, X2OS and CaX2 but does not form XC\S. Which of the following is the element XI (a) B (b) A1 (c) N (d) P. 9. Polarisation is the distortion of the shape of an anion by an adjacently placed cation. Which of the following statements is correct? (a) Maximum polarisation is brought about by a cation of high charge. (b) Minimum polarisation is brought about by a cation of low radius. (c) A large cation is likely to bring about a large degree of polarisation. (d) Polarising power of a cation is less than that of anion. 10. The sum of mole fractions A, £ and C in a solution containing 0.1 mole each of A, B and C is (a) 0.1 (b) 0.3 (c) 1.0 (d) 1/3. 11. A solution contains non-volatile solute of molecular mass M2. Which of the following can be used to calculate the molecular mass of solute in terms of osmotic pressure? (a)
M2 =
(c) M 2 =
^ r rr,T
VRT
/i \ j/ (b) M 2 =
•KRT
(d) M2 :
(
m
V
l \
^
/ 7t
IIRT "
12. The heat of neutralisation of aqueous hydrochloric acid by NaOH isx kcal/mole of HC1. Calculate the heat of neutralisation per mole of aqueous acetic acid? (a) 0.5* kcal (b) * kcal (c) 2x kcal (d) cannot be calculated from the given data. 13. Under the same conditions how many ml of 1 M KOH and 0.5 H 2 S0 4 solutions, respectively when mixed to form a total volume of 100 ml produce the highest rise in temperature? CHEMISTRY TODAY | OCTOBER '05
(a) 67. 33 (c) 40. 60
(b) 33, 67 (d) 50, 50.
14. Which one of the following will favour the reverse reaction in a chemical equilibrium? (a) removal of one of the products regularly (b) increasing the concentration of one of the reactants (c) increasing the concentration of one of the products (d) adding negative catalyst. 15. Which of the following oxides of nitrogen will be the most stable one? ls (a) 2 N 0 2 ( K ) , N 2(jr) + 20 2 ( K ) ; A' = 6.7 x 10 mol L" O 2 Or) = 2.2 x 1030 molL-' (b) 2NO t e ) ^ N 2(g) (c) 2N 2 0 5 fe) 2N-2(g) ' 5 0 2(g) K = 1.2 x 1024 mol L"1 2N 2 f e ) + 0 2 W ; (d"> 2N-0 (s) K = 3.5 x 10" mol L"'.
21. Which of the following plots represents correctly variation of equivalent conductance (A) with dilution for a strong electrolyte?
(a) dilution
dilution
(d)
(C) dilution
dilution
22. The equivalent conductance at infinite dilution of the salt MX is 160.84 ohm"1 cm 2 eq_1. If the transport number of M+ is 0.40, the ionic mobility of A'" in 2 1 ] 16. Which of the following will occur if a 0.1 M solution cm s V~ is 5 (b) 6.7 x 10 ; of a weak acid is diluted to 0.01 M at constant | (a) 3.9 x 1(1 3 • (c) 2.5 x 10~ (d) 1.0 x 10"3. temperature? (a) (b) (c) (d)
[FT] will decrease to 0.01 M pH will decrease percentage ionisation will increase K„ will increase.
23. The reactions : 2NO + 0 2 ^ 2 N 0 2 2CO + 0 : ^ 2C0 2 look to be identical, yet the first is faster than the second. 17. A certain sample of beer has a pH of 10. The The reason is that (a) the first reaction has lower enthalpy change than concentration of hydrogen ions in the beer is the second (a) 10'° M (b) 10- 2 M j (b) the first reaction has lower internal energy change (c) 10-4 M (d) 10~'° M. than the second 18. The decomposition of KCIO, to KC1 and 0 2 on (c) the first reaction has lower activation energy than heating is an example of the second (a) intermolecular redox reaction (d) the first reaction has higher activation energy than (b) intramolecular redox reaction the second. (c) auto redox reaction 24. While studying the decomposition of gaseous N 2 0 5 , (d) none of these. I it is observed that a plot of logarithm of its partial pressure 19. The number of electrons involved in the reduction I versus time is linear. The kinetic parameter obtained of nitrate ion to hydrazine is | from this observation is (a) 8 (b) 7 | (a) specific reaction rate (b) reaction rate (c) 5 (d) 3. (c) energy of activation (d) molecularity. 20. Two platinum wires were dipped in CuS0 4 solution taken in a beaker and then connected to a battery. The 25. A first order reaction is half-completed in 45 minutes. blue colour of copper sulphate disappeared and a gas How long does it needed for 99.9% of the reaction to was found to be evolved at one of the electrodes. The be completed? ! (a) 20 hours (b) 10 hours solution in the beaker now contains (a) platinum sulphate (b) cuprous sulphate (d) 5 hours. (c) 7— hours. (c) sulphuric acid fd) copper hydroxide. 18
CHEMISTRY TODAY | SEPTEMBER '05 40
26. The triad of nuclei is isotonic in (a) 'g C. (c) 'g C,
! 5 7 R
'gF 7
'9 F
2
(b) '6 C,
'74N,
(c) sylvine and fluorspar are halide minerals (d) calamine and zincite are the minerals of calcium.
'98F
35. The first ionisation enthalpy (energy) (kJ mol~') for H, Li, F, Na has one of the following values 1681, 520, 1312, 495. Which of these values corresponds to that of hydrogen? (a) 1681 (b) 1312 (c) 520 (d) 495.
(d) '64C, '74N.
27. Atomic weight of thorium is 232 and its atomic number 90. The number of a-particles and P-particles which-will be lost so that an isotope of lead (atomic weight 208 and atomic number 82) is produced is (a) 4 a + 6P (b) 6 a + 4P (c) 8 a + 2P (d) 10a + 23.
36. When zeolite, which is hydrated sodium aluminium silicate, is treated with hard water the sodium ions are exchanged with (a) H + ions (b) Ca 2+ ions (c) OH- ions (d) S042~ ions.
28. A radioactive sample has initial activity of 28 dpm. Half hour later its activity is 14 dpm. How many atoms of nuclide were present initially? (a) 200 (b) 400 i 37. In electrolvsis of NaCI when Pt electrode is taken (c) 600 (d) 1200. ; then H2 is liberated at cathode while with Hg cathode 29. Gelatin is mostly used in making ice cream in order it forms sodium amalgam. The reason for this is to (a) Hg is more inert than Pt (a) prevent making of a colloid (b) more voltage is required to reduce H+ at Hg than (b) stabilize the colloid and prevent crystallization at Pt (c) stabilise the mixture (d) enrich the aroma. (c) Na is dissolved in Hg while it does not dissolve in Pt 30. ZSM-5 converts (d) concentration of H + ions is larger when Pt electrode (a) alcohol to petrol (b) benzene to toluene is taken. (c) toluene to benzene (d) heptane to toluene. 31. Generally the ionization enthalpy in a period increases but there are some exceptions. The one which is not an exception is (a) Be and B (b) N and O (c) Mg and A1 (d) Na and Mg. 32. If the ionization enthalpy and electron gain enthalpy of an element are 275 and 86 kcal mol~' respectively, then the electronegativity of the element on the Mulliken scale is (a) 2.8 (b) 0.0 (c) 4.0 (d) 2.6
j
38. Which of the following alkaline earth metal oxides shows a coordination number four? (a) BeO (b) MgO (c) SrO (d) CaO.
| 39. A certain metal is used to prepare an antacid, this metal accidentlv catches fire which cannot be put out by using C0 2 based extinguishers. The metal is (a) C 7b) Ca (c) Mg (d) Na. 40. Which of the following reactions is employed to produce ozone in the laboratory? (a) exposure of air to UV light (b) reaction of F2 with H 2 0 at low temperature (c) reaction of S0 2 with H 2 0 2 (d) passage of silent electric discharge through oxygen.
33. When an aqueous solution of sodium chloride is electrolysed using platinum electrodes, the ions discharged at the electrodes are (a) sodium and hydrogen (b) sodium and chloride 41. Identify the correct order of acidic strength of CO;., (c) hydrogen and chloride | CuO, CaO, H 2 0. (d) hydroxy! and chloride. j (a) CaO < CuO < H z O < CO : | (b) H 2 0 < CuO < CaO < C 0 2 34. Pick up the incorrect statement? j (c) CaO < H 2 0 < CuO < C 0 2 (a) asbestos and willemite are silicate minerals | (d) H 2 0 < C 0 2 < CaO < CuO. (b) anglesite and barytes are sulphate minerals 18 C H E M I S T R Y T O D A Y |SEPTEMBER'0541
42. (a) (b) (c) (d)
Thermite is a mixture of 3 parts of powdered A1 and 1 part of Fe 2 0 3 1 part of powdered A1 and 3 parts of Fe 2 0 3 1 part of powdered A1 and 1 part of Fe 2 0 3 2 parts of powdered AI and 1 part of Fe 2 0 3 .
43. Hydrated aluminium chloride is ionic and soluble in water giving (a) Al3+ and CI- ions (b) [A1(H206]3+ and CI" ions (c) [A1C12(H20)4]+ and [A1C14(H20)2]" ions (d) none of these.
49. A certain compound when burnt gives three oxides. The first turned lime water milky. The second turned anhydrous CuS0 4 blue and the third formed an aqueous solution of low pH. The elements present in the compound are (a) C, O and S (b) C, H and Ca (c) C, H and Na (d) C, H and S. 50. (a) (b) (d)
The shape of molecule SF3C13 is trigonal bipyramidal cubic (c) octahedral tetrahedral.
44. Water transported through lead pipes becomes poisonous due to the formation of (a) PbO (b) Pb0 2 (c) Pb(OH)2 (d) Pb 3 0 4 .
51. (a) (c) (d)
The lowest boiling point of helium is due to its inertness (b) gaseous nature high polarisability weak van der Waals forces between them.
45. A solid element (symbol Y) conducts electricity and forms two chlorides PC1„ (a colourless volatile liquid) and TC1„ _ 2 (a colourless solid). To which one of the following groups of the periodic table does Y belong? (a) 13 (b) 14 (c) 15 (d) 16.
52. Which of the following is not an electronic configuration of noble gas? (a) \s22s22p6 (b) \s2 2 2 6 2 (c) \s 2s 2p 3s (d) Is2 2s2 2p6 3s2 3p6.
46. The correct increasing order of extent of hydrolysis in the following is (a) CC14 < MgCl2 < A1C13 < SiCl4 < PC15 (b) CC14 < A1C13 < MgCl2 < PC15 < SiCl4 (c) A1C13 < MgCl2 < CC14 < PC15 < SiCl4 (d) SiCl4 < MgCl2 < A1C13 < PC15 < CC14. 47. Both boron and aluminium show difference in properties from the remaining members of group 13. This is due to the fact that (a) both B and AI have smaller size as compared to other members of the family (b) both B and AI have high values of ionization enthalpy (c) both B and AI have 2 and 8 electrons in their penultimate shell respectively but the remaining elements of this group have 18 electrons (d) none of these. 48. Among the elements of group 15 which of the following properties shows an increase as we move down from nitrogen to bismuth? (a) stability of - 3 oxidation states (b) reducing character of hydrides (c) electronegativity (d) acidic nature of oxides. 18
53. K 2 Cr 2 0 7 is preferred to Na 2 Cr 2 0 7 for use in volumetric analysis as a primary standard because (a) Na 2 Cr 2 0 7 is hygroscopic while K 2 Cr 2 0 7 is not (b) K2Cr207 is hygroscopic while Na 2 Cr 2 0 7 is not (c) K 2 Cr 2 0 7 is pure while Na 2 Cr 2 0 7 is impure (d) none of these. 54. (a) (b) (c) (d)
K3[A1(C204)3] is called potassiumalumino oxalate potassiumtrioxalato aluminate(III) potassiumaluminium(III) oxalate potassiumtrioxalato aluminate(VI).
55. A gasJfis passed through water to form a saturated solution. The aqueous solution on treatment with the AgN0 3 gives a white precipitate. The saturated aqueous solution also dissolves magnesium ribbon with evolution of a colourless gas Y. Identify X and Y. (a) X = C0 2 , Y = Cl2 (b) Jf = Cl2, Y = C0 2 (c) X = Cl2, Y = H2 (d) X = H2, Y = Cl2. 56. Which of the following is a biodegradable pollutant? (a) plastic (b) sewage (c) asbestos (d) mercury. 57. The IUPAC name of the spiro compound,
OC™' CHEMISTRY TODAY |
SEPTEMBER
'05 42
(a) (b) (c) (d)
2-methylspiro[5.4]deca-1,6-diene 2-methylspiro[4.5]deca-l,6-dier!e 8-methylspiro[4.5]deca-l,7-diene 3-methylspiro[5.4]deca-3,7-diene.
58. Two isomeric alkenes A and B having molecular formula C5H9C1 on adding H2, A gives optically inactive compound while B gives a chiral compound. The two isomers are (a) A is 3-chloro-1 -pentene and B is 1 -chloro-2-pentene (b) A is 2-chloro-3-methyl-2-butene and B is 1-chloro3 -methyl-1 -butene (c) A is 3-chloro-2-pentene and B is 2-chloro-2-pentene (d) A is 4-chloro-2-pentene and B. is 4-chloro-2-pentene. 59. When the hybridisation state of carbon atom changes from sp3 to sp2 and finally to sp, the angle between the hybridised orbitals (a) decreases gradually (b) decreases considerably (c) is not affected (d) increases progressively. 60. The energy of the orbitals decreases in the order (a) s > p > sp3 > sp> sp2 (b) p > sp3 > sp2 > sp > s (c) sp3 > sp2> sp> s> p (d) s> sp> sp2 > sp3 > p. 61. When an alkyl iodide (RI) is treated with Na in dry ether, a symmetrical alkane (R2) is obtained. The reaction is called (a) Grignard reaction (b) Fischer-Tropsch reaction (c) Berguis reaction (d) Wurtz reaction. 62. An alkene with molecular formula C4H8 upon ozonolysis gives one mole of propanone and one mole of methanol. The alkene is (a) 1-butene (b) 2-methylpropene (c) 2-butene (d) 2-methyl-2-butene. 63. The treatment of benzene with isobutene in the presence of sulphuric acid gives (a) isobutylbenzene (b) /er/-butylbenzene (c) «-butylbenzene (d) no reaction.
j2 The above transformation proceeds through (a) electrophilic addition (b) benzyne intermediate (c) activated nucleophilic substitution (d) oxirane. 18 CHEMISTRY TODAY |
SEPTEMBER
'05 43
65. Which of the following forms potassium carbonate on boiling with alcoholic KOH solution? (a) dichloromethane (b) tetrachloromethane (c) perchloromethane (d) chloroform. 66. An organic compound Xon treatment with acidified K 2 Cr 2 0 7 gives a compound Y which reacts with I2 and sodium carbonate to form tri-iodomethane. The compound X\s (a) CH3OH (b) CH3COCH3 (c) CH3CHO (d) CH3CHOHCH,. 67. and (a) (b) (c) (d)
Methyl «-propyl ketone on oxidation with K 2 Cr 2 0 7 H 2 S0 4 gives mainly CH3CH2COOH + CH3COOH CH3CH2CH2COOH + HCOOH CH3COOH + HCOOH CH3CH2COOH + C0 2 + H 2 0.
68. Oxidation of benzyl chloride with an aqueous solution of lead nitrate in a current of CO, gives (a) benzaldehyde (b) benzyl alcohol (c) p-nitrobenzyl chloride (d) benzyl nitrate. 69. A compound with molecular formula C 4 H, 0 O 4 on acylation with acetic anhydride gives a compound with molecular formula C,2H18Og. How many hydroxyl groups are present in the compound? (a) one (b) two (c) three (d) four. 70. Which of the following is the weakest acid? OH
(c) HCOOH 71. Diazonium salts are the reaction products between nitrous acids and (a) primary aliphatic amine (b) N-alkyl substituted aromatic amines (c) primary aromatic amines (d) secondary amines. 72. An optically active compound with molecular formula C6H, ,N dissolves in dilute aqueous hydrochloric
acid and releases N 2 gas on treatment with nitrous acid. The compound is NHCH, (a)
(b)
.(c) C6H5CH(NH2)CH3 73. (a) (b) (c) (d)
(d) C6H5 - NH - C2H5.
The abbreviation PDI refers to name of the polymer poly dispersity index Planck's disposal index poly diagonal index.
6.
(b) : u = 2 x l 0 1 4 cm~\ c = v*. = v / o
or, v = cu = (3 x 10IO)(2 x 1014) = 6 x 1024 s"1. 7. (b) : The difference in energy of the actual molecule (experimental value) and energy of the most stable resonating structure is called resonance energy, i.e. E0 — £3. 8. (c) : Since the element X forms XC13, X205 and Ca3X2, therefore, it must be N or P. Since it does form JVCI5, therefore, it must be N since it has no rf-orbitals to expand its covalency from 3 to 5. Therefore, A" must be N.
9. (a) 74. Match list I (name of vitamin) with list II (deficiency result/disease) and select the correct answer using the 10. (c) : The sum of mole fractions of all the components = 1. codes given below the lists. List I List II ,, M7RT (M7\RT I. Ascorbic acid A. Beri-beri II. Retinol B. Cracked lips 12. (d) : AHNMT cannot be predicted unless we know III. Riboflavin C. Scurvy i heat of dissociation of acetic acid. IV. Thiamine D. Night blindness. 13. (d) : 50 ml of 1 M KOH + 50 ml of 0.5 M H 2 S0 4 Codes : will involve complete neutralisation. (a) I-B, II-A, III-C, IV-D 14. (c): Increasing concentration of a product favours (b) I-A, II-B, III-C, IV-D reverse reaction. (c) I-D, II-C, III-B, IV-A (d) I-C, II-D, III-B, IV-A. 15. (a) : Lower the equilibrium constant, greater is the 75. A drug which is structurally related to adrenaline stability. is (a) salbutamol (c) diazepam
16. (c) : On dilution, ionisation increases. (b) salvarsan (d) LSD. ANSWERS
(b) : 1 mol of H 2 0 = 18 g = 6.02 x 1023 molecules 0-06 , „„ , n ?3 Hence 0.06 se H2, 0 = * 6 . 0 2 x 1 0 " molecules 18 21 = 2 x io molecules. 1.
2. (b) : Average kinetic energy depends only on temperature and does not depend upon the nature of the gas.
17. (d) : pH = 10 means [H+] = IO"10 M. 18. (b) : Here one element of KC10 3 is oxidised -2
0
+5
-}
(O —» O,) while the other is reduced (CI —» CI) and hence it is an example of intramolecular redox reaction. 19. (b) : NO, N2H4 To balance N atoms, multiply NO," by 2, we have +5
-2
2N0 3 N2H4 Total O.N. = 2 x +5 Total O.N. = 2 x -2 = +10 =-4 To balance O.N., add \4e~ to L.H.S., we have 3. (a) : For rhombohedral system, 2N0 3 - + 14e~ —» N 2 H 4 a = b = c, a = 3 = v * 90°. Rhombohedral system is an alternative representation or, N 0 3 - + 7e~ -> 1/2 N 2 H 4 of the trigonal or hexagonal crystal systems. Therefore, number of electrons involved in the reduction 4. (b): 1 st line is for 3 —> 2 and 2nd line is for 4 —> 2. of N0 3 " ions is 7. 5. (b) : CI" ion is smaller than B r and K+ is larger 20. (c) : At anode (made of Pt), H : 0 is oxidised more easily than S042~ ions. H+ ions produced combine with than Na 4 . Hence ratio of CP : K+ is smallest. 18
CHEMISTRY TODAY | SEPTEMBER '05 44
SO„2 ions to produce H 2 S0 4 . Cu 2+ ions are deposited on cathode. 0 2 is evolved at anode. 21. ( b ) : Equivalent conductance increases with dilution and ultimately becomes constant. 22. (d) : Ionic conductance of ion = transport number of that ion x Aeq° of strong electrolyte containing that ion = (1 - 0.40) x 160.84 = 96.504 ionic conductance _ 96.504 _ 3 Ionic mobility = —-10 96,500 96,500 23. (c): Lower the activation energy, faster is the reaction. 24. (b) : As it is a reaction of 1st order, t
of O because of extra stability of exactly half-filled 2p-orbitals in N. IE, of Mg is higher than that of Na because of higher nuclear charge and completely filled 3.?-orbital in Mg. 32. (a) : IE + EA = 275 + 86 = 361 k cal mol"1 = 361 x 4.184 = 1510.42 kJ mol"1 1510.42 OD Electronegativity = — — = 2.797 = 2.8 33. (c) : As the reduction potential of hydrogen is lower than that of sodium, it will be discharged at the cathode and chlorine will be discharged at the anode. 34. (d) : Calamine is Z n C 0 3 and zincite is ZnO. Both are minerals of zinc.
[A] 0
35. (b) : IE of H atom is 1312 kJ mol" 1 . 36. ( b ) : Na,ALSi 2 0 8 • * H 2 0 + Ca 2+ . , ,
, 2.303, p N2O5 i.e.. k = log PNjOJ
-
z
from hard water
zeolite
>
CaAI 2 Si 2 0 8 • JCH20 + 2Na" -t + l o g p
°f' 2.303 From slope, k can be calculated. , , , 0.693 . 25. (c) : k = — m i n 45 or,
'99.9%
2.303x45 0.693
=
37. (a) : H + ions are discharged at a higher potential when Hg cathode is used than that using Pt cathode.
N2O5
2.303, log '99.9%
a a
-0.999a
log 10 = 448 min
,1 = 7— hours. 2 26. (a) : (a) has all atoms with A — Z - N same. 27. (b) : 2H Th -> 2£f Pb + * \ a + y 232 = 208 + 4x 90 = 82 + 2 x - y
p
or, x = 6 or, y = 4.
28. (d) : x = ^ ^ l o g — = 2 . 3 x l 0 - 2 m i n - 1 . 30 14 Initially, activity = \N i.e. 28 = 2.3 x 10 -2 x or, N = 1217 = 1200. 29. (b) : Gelatin stabilises the colloids and prevents crystallisation. 30. (a) : ZSM-5 (size selective catalyst) converts alcohol to petrol. 31. (d) : IE, of B is lower than that of Be because in B, a 2p-electron is to be removed while in Be it is the 2\-electron. Similarly, IE, of AI is lower than that of Mg because in Al, a 3/7-electron is to be removed while in Mg it is the 3,v electron. IE, of N is higher than that CHEMISTRY TODAY |
SEPTEMBER
'05
38. (a) : Be shows coordination number of four in BeO which is covalent and has zinc sulphide (wurtzite) structure while all others show a coordination number of six. (NaCl structure) and are ionic. 39. ( c ) : Generally Mg(OH) 2 is used as an antacid. The metal is Mg which burns in C 0 2 atmosphere. 2Mg + C 0 2 - > 2MgO + C. 40. (d) : 3 0 2A
Sl ent
'
fctnc > 20,
discharge
41. (a) : Alkaline earth metal oxides are more basic than transition metal oxides which in turn are more basic than non-metal oxides and thus the acidic character increases from left to right in a period. 42. (b) : A mixture of one part of powdered Al and three parts of Fe 2 0 3 is called thermite. dlssociatio 43. (c) : A i d , • 6 H 2 0 " > [A1C1 2 (H 2 0) 4 ] + + [AIC1 4 (H 2 0)J-
44. (c) : Water in presence of oxygen reacts with Pb (pipes) to form soluble Pb(OH) 2 which gives poisonous Pb 2+ ions in solution. Pb + 0 2 + H 2 0 - > Pb(OH) 2 45. (b) : Element Y belongs to group 14 of the periodic table which forms two chlorides y d 4 (a colourless, volatile liquid) and KC12 (a colourless solid). 46. (a) : Extent of hydrolysis increases in the order: CC14 < MgCl 2 < A1C13 < SiCl 4 < PCI5. 45
47. (c) : Both B and AI have 2 (Is 2 ) and 8 (2s2 2p 6 ) electrons in their penultimate (last but one) shell respectively but the remaining elements of group 13 have 18 electrons in their penultimate shell and hence B and AI show different properties from those of remaining members of group 13. 48. (b) : Reducing character of hydrides of nitrogen family increases as the size of the central atom increases down the group. All other properties stated here decrease down the group. 49. (d) : The compound contains C, H and S as the elements which on burning give C0 2 , H 2 0 and S0 2 as oxides respectively. First oxide (C0 2 ) turns lime water milky, the second oxide (H 2 0) turns anhydrous (white) CuS0 4 blue due to hydration and the third oxide (S0 2 ) dissolves in H 2 0 giving an acid (H 2 S0 3 ) which lowers the pH of the solution. C, H, S are the elements in a compound. C + 0 2 — C 0 2 ; 2H 2 + 0 2 — 2 H 2 0 (1) (II)
s + o2
so2
58. (c) : Only option (c) is correct as shown below. CI CI I
H2
(I)
lime water
CI
CI
CH 2-chloro-2-pentene (B)
optically active
59. (d) : Angle increases progressively. sp3 (109° 28'), sp2 (120°), sp( 180°) 60. ( b ) : As the s-character increases or the ^-character decreases, the energy of the orbital decreases. Thus the order is p > sp3 > sp2 > sp > s. 61. (d) : Wurtz reaction. 62. (b) : Ozonolysis since all the three alkenes will give different products as shown below. (•)0 3 CH3CH2CH — C H2 » CH3CH2CHO + HCHO (ii) Zn/H 2 0
1-buterie
(milkiness) (II)
CuS0 4 • 5H 2 0
colourless
(CH3)2C = CH2
blue
S0 2 + H z O
H 2 S0 3
(III)
(>)o3
CH 3 CH=CHCH 3
> 2CH3CHO
(ii) Zn/H 2 0
insoluble
5H 2 0 + CuS0 4
optically inactive
3-chloro-2-pentene (A)
(III)
C 0 2 + Mg(OH) 2 -4 MgCOj + H 2 0
I
CH3CH2 - C — CH - CH3 —- • CH3CH2 — CH — CH2CH3
J> (CH3)2CO + HCHO
(ii) Zn/H 2 0
CH,
acid, lowers pH of the solution
50. (c) : The shape of SF3C13 molecule is octahedral. 51. ( d ) : He has lowest boiling point due to weak van der Waals forces between its atoms. 52. (c) : All noble gases except He (which has Is 2 ) have ns2 np6 electronic configuration of the valence shell. 53. (a) : Na 2 Cr 2 0 7 is hygroscopic and cannot be used as a primary standard in volumetric analysis. 54. (b) : IUPAC name is potassiumtrioxalato aluminate(III). 55. (c) : Cl 2 + H 2 0 HCl + HCIO; X AgN0 3 + HCl AgCl + HN0 3
63. (b) : C H 3 - C = CH2 + C6H6 isobutene
(CH 3 ) 3 C-C 6 H 5 ferf-butylbenzene
64. (c)
0_Na+ NaOH^ rj- ^ r " N 0 2
white ppt.
2HC1 + Mg
MgCl 2 + H 2 T Y
56. (b) : Sewage is a biodegradable pollutant.
»••«.
9
l
,
'OCt 7
18
io
6
4
ru
3
The reaction occurs by activated nucleophile substitution. 65. (b) : CC14 + 4KOH
-4KC1
> C(OH).4
- H20
HO - CO - OH carbonic acid
> K 2 C0 3 2
2-methylspiro[4.5]deca-l,6-diene C H E M I S T R Y TODAY |
SEPTEMBER
'05 46
66. (d) : Since compound Y reacts with I2 and Na 2 C0 3 to form triiodomethane, therefore, Y must be a methyl ketone. Since Y is obtained by oxidation of X with K.2Cr207, therefore, Xmust be a methylcarbinol, thus X is CH3CHOHCH3. 67. (a) : During oxidation of unsymmetrical ketones, i.e. /7-propyImethy I ketone, the keto group stays with the smaller alkyl group (Popoff's rule) i.e. CH,CH 2 COOH and CH3COOH are formed. CH COCH,CH,CH [O] CH3COOH + CH CH COOH. 3
3
3
2
168 = 4. 42 70. (a) : Phenol is a weaker acid than carboxylic acid. Total number of OH groups HNO,
71. (c) : A r - N H , - j ^ p aromatic 1° amine
Ar-N=NCP diazonium salt
72. (a) : Of all the amines listed, only (a) has the right molecular formula of C 6 H n N. Since it also contains a chiral carbon, therefore, it is optically active. NH,
68. (a) : C6H5CH2C1 - ^ ^ [ C 6 H 5 C H 2 - 0 N 0 2 ] C6HSCHO + HNO, 69. (d) : Mol. wt. of C4H10O4 = 4 x 12 + 10 x l + 4 x 16 = 122 Mol. wt. of acetylated product = C| 2 H| 8 0 8 = 12 x 12 + 18 x 1 + 8 x 16 = 290. Increase in mass due to acetylation = 290 - 122 = 168 amu Increase in mass due to acetylation of one OH group = 42 a.m.u.
M.F. C6H,,N 73. (b) : Poly dispersity index. 74. (d) : Ascorbic acid - scurvy Retinol - night blindness Riboflavin - cracked lips Thiamine - beri beri 75. (a) : Salbutamol is structurally related to adrenaline.
Dear Students, W e know that its too difficult to remember the elements in their correct order in the first three periods of the table. So we are presenting some mneumonics to leam few very difficult things in Chemistry in a very easy way. 1.
The order of hardness (Mohs' scale of hardness) Tall gyroscopes can fly apart, orbiting quickly to complete disintegration or, Those girls can fly and other queer things can do. Talc, gypsum or rock salt, calcite, fluorite, apatite, orthaclase, quartz, topaz, corundum, diamond.
2.
The molecular shape of fructose and glucose There are two simple sugars (monosaccharides) - fructose and glucose - which combine in a specific way to form sucrose. Contributed by Neha Chandak, Nagpur Remember the molecular shape of fructose has five carbons (letter f starts both words) and hexagon is the shape of glucose (letter g in both words).
3.
The elements in their correct order in the first three periods of the table (Hydrogen being omitted and potassium included). Here lies Benjamin bold cry not old friend needlessly. Nature magnifies all simple people sometimes, clots and kings. Hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium (H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, CI, Al, K)
MEMORY
If you have such mneumonics in Physics, Chemistry, Botany or Zoology which can he proved as aid to memory then send them to us. On selection we will publish them with your name in our monthly magazines Physics For You, Chemistry Today and Biology Today. C H E M I S T R Y TODAY |
SEPTEMBER
'05 47
ORGANIC CH 2 NH 2 -NH 2 NaN02/HCl. » Product, Product is
(c) PhH + Ph 3 C - COC1
anhyd. > Ph 4 C A1( ; 1
(d) PhCH = O + ND NHCONH > PhCH = NNHCONH,
CH2Nj
C"=N
(a)
OH"
0 1 8 - CH,
NH—NH
>N = N Compound VT(C 1 0 H n N)
(a)
dil.H2S04
MQ CH2N2/sunlighil
ro followed by steam>
(a)
catalyst' Product,
(b)
[ O
O - (b) NH. (d)
(c)
Product is
ro NH.
(0
NH,
C-=N
(c)
(d)
Which will not perform iodoform reaction with I 2 /OH ? (a) CH 3 COCH 2 CH 3 (b) CH,CONH 2 (c) C H.COCH, 3 .CH, (d) ( C H 3 ) 2 C H C H 2 C O C H ^ C H 2 C H 2 C H 3 In which of the following reactions the product written is not the main product ? (a) CH 2 = CHCH 2 Cl(excess) + Mg > CH 2 = CHCH 2 - CH 2 CH = CH 2 (b) C 1 C H 2 - C = CH 2 + Mg
A compound of formula C 6 H e O on reaction with excess Na produces 238 litres H 2 (at N.T.P) per Kg of the compound. The compound will be (a) PhOH (b) CH 2 C = C - 0 - C H , C = C - H (c) CH — C - C EE C - CH 2 CH 2 OH (d) H - C = C - CH(OH) - CH 2 C = CH Each of the following compound undergoes reaction with bleaching powder. The yield of chloroform is minimum in which case ? CH 2 CHOHCH 3 CH 2 COCH 3
CH 2 COCH 3
CH,CHOHCH,
> C 1 C H 2 - C = CH 2
Br
MgBr
OMe
Contributed by : Nirmal Singh, Chemistry Classes for IIT-JEE, Kanpur (Mob. : 09839105810) C H E M I S T R Y T O D A Y I FEBRUARY '08
Starch is a polymer of (A) and cellulose is a polymer of (B). (A) and (B) are (a) a-glucose, (3-fructose (b) p-glucose, a-fructose (c) a-glucose, a-fructose (d) a-glucose, P-glucose For coupling reaction of phenol the best medium is (a) a buffer containing 0.1 M BC1 and 0.1 M BOH (ptf b BOH = 9) (b) a buffer containing 0.1 M HA and 0.1 M NaA ( p ^ = A- = 9) (c) 0.1 M NaCl (d) a buffer containing 0.1 M HA and 0.1 M NaA (P* =9) In which of the following the formation of product in first reaction is faster than that in second reaction ? (a) (i) PhH + P h C l - * A1C1,
, (A) is
(a) Br (c) There are following four statements regarding hydrolysis of acid derivatives : I.
anhyd.
(ii) PhH + CH, : C H C H 2 C l ^ r > (b) (i) P h N 0 2 " ^ >
I
OH ^
k +s
Me Ph (a) MeOMe (c)
heat
•Me
II.
>
is less reactive than
COOMe O
N Q 2 - < 0 ) - NH - C - Me is more reactive than 0 II NH - C - Me.
f ^ O 1 III. L ^ ^ ^ - Q is less reactive than
Me O Me Ph
0
Q*
O
(b) PhOH
Me Ph
r ® -
MeO
Product. Product is
(d)
HO
MeO-(^^)-COOEt NO
Br, - Fe
(ii) PhNHAc (c) (i) p-Cresol + sodamide — > (ii) Benzyl alcohol + sodamide (d) (i) HCHO + H 2 0 > (ii) CCI3COCCI3 + H 2 0 >
/^/OCHO
0
XV. M e - C - O - C H j O II Me - C - S - CH 3 .
js
jess
reactive
than
Of these the correct statements are » ( A ) , (A) is
(a) i,n,m (c) 1, iv
(b) n,m,iv (d) i, 11, in, iv
An organic compound (A) {C10H12} on treatment with hot acidic KMn0 4 gives a dibasic acid which on monosubstitution gives a mixture of three isomeric product. (A) is (a)
(b) Pr(«)
(c)
-Vinyl
(d) None of these •Vinyl
B C H E M I S T R Y TODAY I FEBRUARY '08
Consider four reactants : (I) PhCH 3 (II) PhCH2Cl (m)PhCHCi 2 (rv)Phcci 3 Consider bromination of each compound in presence of Fe catalyst. The ratio of w-product to p-product in four m(A) m(5) m(C) m(D) cases is represented by ^ J y ^ J y p ( C ) and p ( D ) . Which of the following is correct ? (a)
m(A) P(A)
m(D) P(D)
(b)
m(C)
>
P(C)
m(5) P(B)
P(D) (c) — > m(A) p(A)
(d) Both (b) and (c)
17. Column (A)
Column (B)
Al EtOH
Bl
ester
52
ether
53
ethylene
A 2 EtOH A3 EtOH
Conc.H 2 S0 4 383 K 413 K 433 K (i) MeCOOH ^
A4 EtOH (ii) Pyrolysis
51
(a) (b) (c) (d)
Al - 5 1 , A 2 - 5 2 , A3 - S3 A2 - 52, A3 - 53, A4 - 53 Al - 51, A3 - 53, A4 - 53 Al - 52, A2 - 53, A3 - 53 When 2-methylidene cyclobutanol is treated with dil. H 2 S0 4 , (A) is obtained as major product. (A) is (a)
(b)
(c)
(d)
-CH 2 CH(OH)Me
^^
CHr, — CH — COCH2
(b)
CH2 = CHCH(OH) - CH2 J p y
- CH2COMe
CH, = CHCOCH, (d)
CH2COMe
CH2 - CH - C H ( O H ) C H 2 - ^ Q V CH,CHMe I OH OH OH Me PhCH2 - N + - CH 2 COCH 3
Product.
CH2CMe3 Product is
Me
(a) PhCH2 - N - CHCOCH3 CH2CMe3 Me ^-CHjPh I N C H (b) ^COCH3 CH2CMe'33 Me (c) P h C H - N1 - C H C / C H , C M e 3 2 \COCH3 Me I (d) PhCH - N - CH-jCOCH, CH 2 CMe 3 SOLUTIONS
OH OH
CH2 —™ CH — CH — CH2
CH2CH(OH)Me
OH on treatment with Mn0 2 gives
(c) (c) (c) (d)
(d) (a) (b) (d)
(b)
(b)
(d)
10
(a) (c)
(d) (a)
15 20.
(d) 13
• • Note : Chem Challenge published in January issue was contributed by Nirmal Singh
Forthcoming Competitive Exams CBSE P M T Preliminary Exam IIT-JEE West Bengal JEE MGIMS CBSE AIEEE AFMC BHU P M T Screening BITSAT CBSE P M T Mains Exam DPMT DCE BHU P M T Mains B C H E M I S T R Y TODAY I FEBRUARY '08
(a) (c) (c) (b)
April 6 April 13 April 20 April 20 April 27 May 4 May 7 May 9 to 12 June May 11 May 18 May 31 June 15
CHEM
emus RULES All students preparing for PMT/PET examinations can participate in Chem-Genius Contest. Answers marked only on the entry form of the magazine / photocopy of form will be accepted. More than one response to a question will be disqualified. Prizes • 1st Prize - LG Mobile phone • 2nd Prize - Adidas Bag • 3rd Prize - MTG Books (worth Rs. 500/-) The entries with maximum number of correct answers for three consecutive months (February '08 - April '08) will be awarded 1 st prize. 2nd and 3rd prize will be given to the next maximum scorers. In case of a tie, the winners will be decided through a lucky draw. The decision of the editor will be final and binding in all cases and will not be a matter for consideration of any court and no correspondence will be entertained. Name and photograph of the prize winners of this contest will be published in the June issue of 2008. MTG is not responsible for any postal delays, transit losses or mutilation of entries. Last Date The entries should reach on/betore 29 lh February '08 to Chem-Genius Contest-3, 406, Taj Apartment, Ring Road, Near Safdarjung Hospital, New Delhi-29. [Note : Enclosures include a passport size photograph and a photocopy of age proof.] The result of contest -2 (November '07 - January '08) will be published in March '08 issue. Ustic acid is a natural compound found in lichens. Which statement correctly represents four of the functional groups present in ustic acid? h3Cx
CH
3
^o c
H—C—OH 0^JL/C02H
hoAAOH
(a) (b) (c) (d)
H Carboxylic acid, ketone, aldehyde and alcohol Ether, ketone, alcohol and aldehyde Carboxylic acid, ketone, phenol and alcohol Ester, phenol, carboxylic acid and ketone Which of the following constitutes irreversible colloidal system in water as dispersion medium?
B
C H E M I S T R Y TODAY I FEBRUARY '08
(a) Clay (c) Fe(OH)3
(b) Platinum (d) All of these
The second electron gain enthalpies (in kJ mol -1 ) of oxygen and sulphur respectively are (a) - 780, +590 (b) - 590, + 780 (c) + 590, + 780 (d) + 780, + 590 Which one of the following chlorides will not fume in air? (a) BiCl, (b) CCL i5 (d) None of the above. (d) PCI,
4.
Partition coefficient of benzoic acid-ether-water in favour of ether is 2. A solution containing 8 g/litre benzoic acid in ether layer is shaken with 2 litre water. The concentration of acid in water layer (b) 2 (a) 1 3 (d) 4 (c)
(a) (b) (c) (d)
Of the five AH values required to calculate a lattice energy using the Born-Haber cycle, the one that is most difficult to measure is the electron affinity of the non-metal the heat of formation of gaseous atoms of the nonmetal the ionisation energy of the metal the heat of sublimation of metal
(a)
If the distance between Na+ and Cl~ ions in sodium chloride crystal is X pm, the length of the edge of the unit cells is (a) 4X pm (b) X/4 pm (c) XII pm (d) IX pm The correct sequence in which bond order decrease in 0 2 , 0 J , 0 j and O§" is such that (a)
02>02>02>02-
(b)
> 0 2 > 02~ > 0 2
(c)
02>02~>02>02
(d)
02>02>02~>02
^
4K
15. The enthalpy changes for two reactions are given by the equations 2Cr ( s ) + ~ 0 2(g ) —> Cr 2 0 3 ( j )
AH = -1130 kJ
c ( J ) + -o 2 ( g ) ^co ( s )
AH = -110 kJ
What is the enthalpy change, in kJ, for the reaction? 3C(S) + Cr 2 0 3(s) —> 2Cr(s) + 3CO (g) ? (a) - 1 4 6 0 (b) -800 (c) + 800 (d) + 1020 16. Arsine (AsH 3 ) is a molecular hydride of a group V element. The most likely structure for the arsine molecule in the vapour phase is H H 90° K 120° 1 ,As As ) (b) (a) H—As— -H
£i
As (C)
10. Hydrazine reduces Fehling solution to (a) CuO (b) Cu 2 0 (c) Cu + 0 2 (d) Cu(OH) 2 The final product of the following reaction is
IID >A (a) (b) (c) (d)
MCQ'i
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o O O O
Payment will be made after the MCQs are published. Kindly note that each question should be complete. Payment will be made only for complete questions. Preference will be given to the reader sending the maximum complete and correct questions. Other conditions apply. The decision ofthe Editor, MTG shall be final and binding.
B C H E M I S T R Y TODAY I FEBRUARY '08
Match list I with list II and select the correct answer using the code given below List I Successive ionization energies (kJ mol"1)
(a) (b) (c) (d)
List II Elements
1.
IE] 2080
IE2 3963
IE, 6130
(«)
H
2.
520
7297
11810
(b)
Li
3.
900
1758
14810
(c)
Be
4.
800
2428
3660
id) (e)
B
1. 1. 1. 1.
(c), (a), (d), (e),
2. 2. 2. 2.
(b), (c), (a), (b),
3. 3. 3. 3.
{d), (b), (b), (c),
4. 4. 4. 4.
Ne
(e) (d) (d) (d)
(c) In k = A - EJRT (d) k = In A + In EJRT The solubility product for SrF 2 is 7.9 x 10~ n . A solution is 0.01 M in NaF. The minimum concentration of SrCl2 in the solution required to start the precipitation of SrF 2 is equal to 5 (b) 0.79 x 10"6 M (a) 0.89 x 10~ M 8 (d) 0.89 x 10"7 M (c) 0.79 x 10" M 34. Ellution in the chromatography is the process for (a) crystallization of compound (b) separation of compound (c) extraction of compound (d) distillation of compound 33
If phosphate is present as an interfering radical in a mixture but III, IV, V groups and Mg 2+ are absent, then
Which is the constitutional isomer of the given compound ?
(a) PO^"" must be removed before the analysis of III group and onwards (b) PO^ - will not interfere (c) PO4 - interferes in III group only (d) Interference of PO^ - is must whether III group and other groups are present or not.
(a)
(b)
(c)
(d) both (a) and (c)
Benzene diazonium chloride when reduced with sodium sulphite yields (a) chlorobenzene (b) benzene (c) phenyl hydrazine chloride (d) phenol Consider the following equilibrium C H nCH -1 ' 2 CH3CH2CH2CH2CH3
CH2CH 2CH ^
H
Magnetite, Fe 3 0 4 can be converted into metallic iron by heating with carbon monoxide as represented by this equation. Fe 3 0 4(l) + 4 CO te) - » 3 Fe (j) + 4 C0 2(g) How many kilograms of Fe 3 0 4 must be processed in this way to obtain 5.00 kg of iron if the process is 85% efficient? Substance Molar mass Fe 3 0 4 232 g mol' 1 (a) 6.92 kg (b) 8.15 kg (c) 20.8 kg (d) 24.4 kg Which of the following is an unsaturated acid? (a) Linoleic acid (b) Stearic acid (c) Myristic acid (d) Laurie acid Which of the following curve gives the variation
Which of the following best describes the equilibrium constant K of this interconversion? (a) K< 1 (b) K> 1
of A~ with 4 c
t
(c) K= 1 (d) K cannot be deduced from this information Which of the following expression gives the effect of temperature on the rate constant? (a) In k = In A - EJRT (b) In k = In A + EJRT 72
C H E M I S T R Y TODAY I FEBRUARY '08
for CH 3 COOH?
t
Vc
Vc (a)
(b) A„
A„
decay (a) (3-emission (b) cx-emission (c) [^-emission (d) K-electron capture 46. For anionic hydrolysis, pH is given by
t Vc (d) None of these
(c)
(a) pH = i p K w - i p K f e 2
A,
(a) (b) (c) (d) 40, (a) (b) (c) (d)
Which of the following reaction is said to be entropy driven? Endothermic reaction with positive entropy change and high temperature Endothermic reaction with negative entropy change and low temperature Exothermic reaction with positive entropy change and high temperature Exothermic reaction with negative entropy change and low temperature
(b) pH = ^ pK„
The size of the nucleus is approximately 1/100th of an atom l/1000th of an atom 1/10000th of an atom 1/100000th of an atom
(c) - 243 kJ
(b) - 88.8 kJ
[COC1(NH3)3(H20)2]C12
(b) [Co(NH 3 ) 3 (H 2 0)Cl 3 ] (c)
the
Na is the more stable isotope of Na. Find out the Na can undergo radioactive
[CO(NH3)3(H20)2C13]
(d) tCo(NH 3 ) 3 (H 2 0) 3 ]Cl 3 Which of the following does not represent a detergent molecule? (a)
CH3(CH2)nCH2-^Q>—OCH2(CH2)12CH3
(b) CH 3 (CH 2 ) n CH 2 (c)
44. A metal nitrate on reaction with KI gives black precipitate and with excess KI gives orange solution. The metal ion is (a) Hg2+ (b) Pb 2+ 2+ (c) Cu (d) Bi 3+ process by which
47. What is the value for AG° when [Ag + ] = [Cu 2+ ] = 1.0 M? (a) - 44.4 kJ
(a)
C0 2 H
23
H = l p K H ,+ l p K a + l l o g C
The hypothetical complex chlorodiaquatriamminecobalt(III) chloride can be represented as
42 Which of the following does not show stereo isomerism H CH, CH, CH, CO-HN / CO-NH (a) ^ N H - C O ^ (b) ^ H N - CO CH, H H H CO,H I H-C-OH (c) CH 3 CH 2 C0 2 H (d) H - CI- O H
45.
P
(d) None of the above
(d) - 374 kJ
41. Which of the following ion is coloured? (a) Cu+ (b) Cu2+ 4+ (c) Ti (d) V 5+
43. Argol, a brown crust formed during fermentation of grape juice contains (a) C 0 2 (b) Fuse oil (c) Potassium hydrogen tartarate (d) Lye
(c)
^logC
-
o
-
SOlNa
CH3(CH2)9CH2-^Q>— 0(CH 2 ) 2 0(CH 2 ) 2 0(CH 2 ) 2 0H
(d) CH 3 (CH 2 ) I2 CH 2 C0 2 - Na+ Mark the false statement. (a) A salt bridge is used to eliminate liquid junction potential (b) The Gibbs free energy change, AG is related with electromotive force E as AG = - n FE (c) Nernst equation for single electrode potential is E=E
RT
(d) The efficiency of a hydrogen-oxygen fuel cell is 23%. B CHEMISTRY TODAY I FEBRUARY '08
(a)
The structure for neo-heptyl alcohol is CHoCHi i CH3CH2-C-OH
(a)
CH 3 I -CH2-CI COOCH,
(b)
(c)
-CH2-CHI CI
(d)
CH^CH^ CH3 (b)
CH3- C-
CH2CH2CH2OH
CH3
CH3-C-CHCH2CH3
I I
H3C
(d)
OH
n - C 7 H 15 OH Which is the decreasing order of stability?
(i)
CH3-CH-CH3
(iii) C H 3 C H C 0 C H 3 (a) (i) < (ii) < (iii) (c) (iii) > (i) > (ii)
(ii)
CH3-CH-0-CH3
(b) (i) > (ii) > (iii) (d) (ii) > (iii) > (i)
Which of the following pairs of compounds are enantiomers? CH,
(a)
HHO-
CH3
-OH -H
and
HOHO-
HHO-
-OH -H CH 3
-H -H CH 3 CH 3
CH 3 CH 3 (b)
and
-CH
2
-CH-
I CN
Cyclohexanol is dehydrated to cyclohexene on heating with conc. H 2 S0 4 . If the yield of this reaction is 75% how much cyclohexene will be obtained from 100 g of cyclohexanol? (a) 61.5 g (b) 75.0 g (c) 20.0 g (d) 41.0 g
CH3 (c)
- C H , - CH— I COC 2 H 5
HH-
OH -OH
CH 3
CH, CH, (c) HO•H -H and HOHO-H H" -OH CH, CH 3 CH 3 CH, H-OH and HO-H (d) HO"H H-OH CH, 13 CH 3 Acrilan is a hard, horny and a high melting material. Its structure is B C H E M I S T R Y TODAY I FEBRUARY '08
Number of n electrons present in naphthalene is (a) 4 (b) 6 (c) 10 (d) 14. An ester (A) with molecular formula C 9 H 10 O 2 was treated with excess of CH 3 MgBr and the compound so formed was treated with conc. H 2 S0 4 to form olefin (B). Ozonolysis of B gave ketone with formula C 8 H g O, which shows positive iodoform test. The structure of A is (a) CH 3 CH 2 COC 6 H 5 (b) C 6 H 5 COOC 2 H 5 (c) C 6 H 5 COOC 6 H 5 (d) CH 3 COC 6 H 4 COCH 3 . What is the concentration of nitrate ions if equal volumes of 0.1 M AgN0 3 and 0.1 M NaCl are mixed together? (a) 0.1 N (b) 0.2 N (c) 0.05 N (d) 0.25 N 100 mL of 1.0 M HC1 are mixed with 75 mL of 1.0 M Na 2 C0 3 . The resulting solution will be (a) acidic (b) basic (c) neutral (d) amphoteric. The density of H 2 S (mol wt. 34) at 27°C and 2 atm pressure is (R = 0.0821 atm/mol K) (a) 2.76 g/L (b) 27.6 g/L (c) 2.76 mg/L (d) none of these. The standard reduction potentials for the two half cell reactions are given below Cd w , £° = - 0.40 V Ctf\aq) + 2eAg\aq) + e-^Aj>(s),E>
= 0.80 V
The standard free energy change for the reaction
2Ag + (a?) + Cd (j) • • 2Ag (j) + C d 2 + W is given by (a) 115.8 kJ (b) -115.8 kJ (c) -231.6 kJ (d) 231.6 kJ A neutral fertilizer among the following is (a) CAN (b) ammonium sulphate (c) ammonium nitrate (d) Urea. The correct order of basicities of the following compounds is (1) CH3— c t
iNH
(2) C H 3 - C H 2 - N H 2
-NH2
O II CH3-C-NH2.
(3) (CH 3 ) 2 NH
(4)
(a) 2 > 1 > 3 > 4 (c) 3 > 1 > 2 > 4
(b) 1 > 3 > 2 > 4 (d) 1 > 2 > 3 > 4.
50 mL of 10 N HCl, 25 mL of 12 N HCl and 40 mL of 5 N HN0 3 were mixed together and volume of the mixture was made 1000 mL by adding water. The normality of the resulting solution will be (a) I N (b) 2 N (c) 3 N (d) 4 N. The oxidation number of Co in [Co(NH 3 ) 3 ](N0 2 ) 3 is (a) + 3
(b) 0
(c) - 3
(d) 6
The reaction (CH 3 ) 3 C - Br
(CH 3 ) 3 C - OH is
(a) elimination reaction (c) free radical reaction
(b) substitution reaction (d) addition reaction.
A compound formed by elements A and B has a cubic structure in which A atoms are at the corners of the cube and B atoms are at the face centres. The formula for the compound is (a) A2B3 (b) AB3 (C) A3B (d) A3B2. Which of the following forms a toxic substance in blood by combining with haemoglobin? (a) carbon dioxide (b) carbon monoxide (c) oxygen (d) methane. Which of the following rate law has an overall order of 0.5 for reaction involving substances x, y and z? (a) Rate = k(Cx)(Cy)(Cz) (b) Rate = k{Cx)°\Cy?\Cf * (c) Rate = k ( C x y \ C y r ( C z f (d) Rate = k(Cx)(Cy)0-5 / (Cz)2 In phosphorus pentoxide each P atoms is linked to (a) 4 oxygen atoms (b) 2 oxygen atoms (c) 3 oxygen atoms (d) 10 oxygen atoms.
^ J ^ + CHClBr 2 •
Me 3 COK^ p r 0 £ j u c t
Predominant product is «
^
(c)
CI CI Me
(b)
(d) Me
Which of the following transition have minimum wavelength? (a) n 4 —» n1 (b) n 2 —> n1 (c) « 4 —» n 2 (d) n 3 —> «! The Ksp of Mg(OH) 2 is 1 x 10~12. 0.01 M Mg(OH) 2 will precipitate at pH = (a) 3 (b) 9 (c) 5 (d) 8 Matte contains mainly (a) Cu 2 S (b) Fe (c) CuS and Fe 2 S 3 (d) Cu 2 S and FeS In P0 4 ~ ion, the formal charge on each oxygen atom and P - O bond order respectively are (a) - 0 . 7 5 , 1.25 (b) - 0 . 7 5 , 1.0 (c) - 0 . 7 5 , 0 . 6 (d) - 3 , 1 . 2 5 . The IUPAC name of CH 3 CH = CHCOOC 2 H 5 is (a) ethylbut-l-enoate (b) ethylbut-2-enoate (c) ethylprop-2-enoate (d) none of the above. If the observed and theoretical molecular mass of NaCl is found to be 31.80 and 58.50, then the degree of dissociation of NaCl is (a) 83.96% (b) 8.39% (c) 90% (d) 100% For the redox reaction Mn0 4 " + C 2 0 4 2 ~ + H + - 4 Mn2+ + C 0 2 + H 2 0 Correct stoichiometric coefficients of Mn0 4 ~, C 2 0 4 2 - and H + are (a) 2 , 5 , 1 6 (b) 1 6 , 5 , 2 (c) 5 , 1 6 , 2 (d) 2,16,5. (a) (a) (b) (c) (d)
Which of the following is not a strong electrolyte? NaCl (b) K N 0 3 (c) NH 4 OH (d) FeS0 4 . Which of the following is correct for lyophilic sol? Irreversible sol Formed from inorganic substances Readily coagulated by addition of electrolyte Self stabilized.
In the stoichiometry of natural /awja.vzYe-a zeolite with formula Na l [(A10 2 ) 56 (Si0 2 ) 136 ], 250H 2 0 the value of x is (a) 56 (b) 136 (c) 250 (d) none of these. B C H E M I S T R Y TODAY I FEBRUARY '08
STEM stands for (a) scanning transmission electron microscope (b) scanning tunneling electron microscope (c) both (a) and (b) (d) none of these
Which isomeric form of benzene hexachloride is used as insecticide? (a) a-form (b) (3-form (c) Y-f° r m (d) 8-form.
1 g atom of an a-emitting nucleide \ X (half life = 10 hours) was placed in a sealed container. 4.52 x 1023 He atoms will accumulate in the container in (a) 4.52 hrs (b) 9.40 hrs (c) 10.00 hrs (d) 20.00 hrs.
( a ) neutral ( c ) acidic
The half lives of two radioactive nuclides A and B are 1 and 2 min. respectively. Equal weights of A and B are taken separately and allowed to disintegrate for 4 min. What will be the ratio of weights of A and B disintegrated? (a) 1 : 1 (b) 5 : 4 (c) 1 : 2 (d) 1 : 3. Which of the following is not the extensive property? (a) Gibbs free energy (b) Enthalpy (c) Entropy (d) Viscosity. (a) (b) (c) (d)
Peptization involves disintegration and then condensation condensation then disintegration adsorption of common ions then disintegration precipitation of charged colloids.
Which of the following does not contain P - O - P bond? (a) Isohypophosphoric acid (b) Diphosphorous acid (c) Diphosphoric acid (d) Hypophosphoric acid. The magnetic moment of a transition metal ion is found to be 5.92 BM. The number of unpaired electrons present in it is (a) 2 (b) 3 (c) 4 (d) 5. The flocculation value is expressed in terms of (a) millimole per litre (b) mol per litre (c) gram per litre (d) mol per millilitre. C EE N
CH 3 MgBr
~> Q
3
>F
OCH 3 The product 'P' in the above reaction is c h
/ ^
o h
Acetamide is
(a)
(b) (c) (d)
(a)
(c)
OCH3 B C H E M I S T R Y TODAY I FEBRUARY '08
The complex ion [CU(NH3)4]2+ is tetrahedral and paramagnetic tetrahedral and diamagnetic square planar and paramagnetic square planar and diamagnetic.
A solid AS has NaCl structure. If the radius of cation A+ is 170 pm, calculate the maximum possible radius of the anion B~. (a) 210.3 pm (b) 397.4 pm (c) 410.6 pm (d) 347.9 pm. (a) (b) (c) (d)
The size of ionic species is correctly given in order Cl 7+ > Si4+ > Mg 2+ > Na + Na + > Mg 2+ > Si4+ > Cl 7+ Na + > Mg 2+ > Cl 7+ > Si4+ Cl 7+ > Na" > Mg 2+ > Si 4+ .
The heat of combustion of carbon is - 94 kcal at 1 atm pressure, the intrinsic energy of C 0 2 is (a) + 9 4 kcal (b) - 94 kcal (c) + 4 7 kcal (d) - 47 kcal. In a catalytic conversion of N2 to NH 3 by Haber's process, the rate of reaction expressed as change in the concentration of ammonia per time is 40 x 10~3 mol~V . If there are no side reaction, the rate of the reaction as expressed in terms of hydrogen is (a) 60 x 10"3 mol L"< s"1 (b) 20 x 10"3 mol L"1 s" (c) 1200 mol L"1 s- 1 (d) 10.3 x 10~3 mol L"1 s"1. The general order of reactivity of carbonyl compounds for nucleophilic addition reaction is (a) H 2 C = O > R 2 C = O > Ar 2 C = O > RCHO > ArCHO (b) H 2 C = O > RCHO > R 2 C = O > ArCHO > Ar 2 C = O (c) ArCHO > Ar 2 C = O > RCHO > R 2 C = O > H2C = O (d) Ar,C = O > R 2 C = O > ArCHO > RCHO > H2C =
CO-CH3
CH3
(b) basic (d) amphoteric.
o
Brown haematite is (a) Fe 2 0 3 (c) 2Fe 2 0 3 .3H 2 0 (a) (b) (c) (d)
(b) FeS 2 (d) none of these.
Alumina is insoluble in water because it is a covalent compound it has high lattice energy and low heat of hydration it has low lattice energy and high heat of hydration Al 3+ and O 2 ions are not excessively hydrated.
Then
The prefix neo means a carbon atom having four alkyl groups, position of alcohol group should be at CJ.
Presence o f - 7 effect in a carbocation decreases delocalisation of the positive charge and hence decreases stability of the carbocation and vice versa. Thus the carbocation (iii) having -COCH 3 grouping is the least stable, follwed by (ii) having -OCH 3 grouping, followed by (i) having only alkyl group. A pair of molecule which cannot be superimposed on its mirror image (i.e., asymmetrical) related to each other as an object to its mirror image are known as enantiomers, So, CH 3
H-
CH 3
and
-OH -H
HO-
-H -OH
HOH-
CH 3
CH 3
are enantiomers. Acrilan is a cyanide compound. It has a structure -CH2-CH-
I
CN
0.1xV=M2x2V 01 - 0.05 M, " 2 ' Na 2 C0 3 + 2HC1 2NaCl + H 2 0 + C 0 2 Meq of HCl = 1.0 x 100 Meq of Na 2 C0 3 = 2 x 1.0 x 75 = 150 Thus, Na 2 C0 3 is in excess, and being the salt of weak acid (H 2 C0 3 ) and strong base (NaOH), undergoes hydrolysis to produce basic character. Na 2 C0 3 + 2H 2 0 2Na+ + 20H" + H 2 C0 3 PV^JILRJ M Tn RT , v RT „
p
+ H2O
The weight of cyclohexene formed 82 x 100 75 = g ~ 1 0 0 — loo Naphthalene has a structure,
r
H3C- C- N H
6
(A)
2 5
CH 3 MgBr
CH2 conc. H,SO,
> C6H5C-OH 5
•o
NH, » H3C- C -
NH2
II
0
..
:or
CH3-C-NH2<
I
/ \
NH
> (CH 3 ) 2 NH
C H 3 - C;
NH,
CH 3
> C 6 H 5 - c — ~ > CGHS- c - CH;•3
(B) I v ; CH 3
> C 6 H 5 COONa + CHI 3 AgN0 3(a9) + NaCl(ll9) - > NaN0 3(a9) + AgCl(J) N O j ions remain in the solution. If V mL each of the two solutions be mixed, the volume of the resulting solution = 2V
+
> H 3 c - c = nh2
So, the correct order of basicity is
|
O
Iodoform
C - C - NH 2 CH 3 - C H 2 - N H 2 > CH 3 -
o
c-
NH2
NV=N1V1+N2V2 + N3V3 1000 = 50 x 10 + 25 x 12 + 40 x 5 1000 = 500 + 300 + 200 1000= 1000 1000=i 1000 So, 1 N is the normality of resulting solution. Oxidation state of NH 3 = 0 and N 0 2 = - 1 So, [Co(NH 3 ) 3 (N0 2 ) 3 ]
Nx Nx Nx ^
B C H E M I S T R Y TODAY I FEBRUARY '08
x + (0) + 3 x ( - 1) = 0; X - 3 = 0; JC = + 3 The replacement of an atom or group from a molecule by a different atom or group is known as substitution reaction. (CH3)3C - Br - I I ^ ( C H 3 ) 3 C - O H Substitution reaction
Number of corner atom (A) = 8 x ^ = 1 number of face centre atom (B) = 6 x ^ = 3 Hence formula for the compound is AB3. CO dissolve more rapidly in blood than oxygen. Rate = k (C,)1-5 (Cv)-1 (Cz)° Adding all exponential term = 1.5 + ( - 1) = 0.5 The structure of phosphorus pentoxide is
:o:
So, each P atom is linked to 4 oxygen atoms, one by double bond and other three by single bond. CHClBr2 + Me3COK —> CClBr2 :CClBr Chlorobromo carbene (: CClBr) undergoes addition. r, he j-. 1 K °r K Thus, a decrease in wavelength represents an increase in energy for ra4 transition. Greater the energy difference will follow lower wavelength. Thus, for n4 - n, transition wavelength would be minimum. Mg(OH)2 ± Mg 2+ + 201T the solubility product Ksp of Mg(OH)2 = [Mg]2+ [OH"]2 1 x 10-12 = [0.01][OH-]2 [OH-]
2
= i ^ = lxlO- 1 0 or [OH-] = 10-
[H+][OH_] = 10-14 or [H+] =
10"
:
= 10'
pH = - log[H+] = - log 10"9 = 9 During metallurgy of Cu after smelting, mixture of Cu2S and FeS is left, which is called matte. 82
C H E M I S T R Y TODAY I FEBRUARY '08
Total number of electrons present in the valence shell of phosphate ion = 5 + 8 = 13 Total number of electrons involved in bond formation in P043" ion = 13 - 3 = 10 10 3 Number of bonds in P 0 4 = — = 5 Average P—O bond order = ^ = 1.25 The average formal charge on each 'O' atom. Total charge _ -3 '=-0.75 Total entity of 'O' atom ~ T CH3CH = CHCOOC2H5 the IUPAC name is ethylbut-2-enoate. . 58-50 = 1-8396 31-80 i-1 1-8396 1 a == 0 • 8396 or 83 • 96% m-1 2-1 The balanced equation is 2Mn04 + 5C 2 04 _ + 16H + -> 2Mn 2+ + 10C0 2 + 8H 2 0. NH4OH is weak electrolyte. Lyophilic sols are self stabilised reversible, organic macromolecules and are not coagulated by addition of electrolytes. 31. Here Si0 2 and H 2 0 do not carry any charge. The charge present in A102 unit is - 1 (+ 3 on Al and - 4 on two O-atoms). Thus negative charge present on 56 A102 units is - 56. Therefore 56 Na + ions are present in one molecule of faujasite. STEM stands both for scanning tunneling electron microscope and scanning transmission electron microscope. 1 g atom = 6.02 x 1023 atoms = N0\ tm = 10 hrs No. of atoms disintegrated = No. of a-particles = No. of He atoms = 4.52 x 1023 No. of atoms still present = 6.02 x 1023 - 4.52 x 1023 = 1.50 x 1023 , 0.693 _ 0.693'=0.0693 . hr 10 '•112 6.02 xlO 2 t = 2.303 log 0.0693 ° 1.50x10 2.303x0.06021 = 20 hours 0.0693 For A ForB T = 4 min T - 4 min tm = 1 min h/2 ' ^ min N0 = x (say) N0 = x (say) n = 4/2 = 2 n = 4/1 =4 No
_ x _ X
2" 24 16 A disintegrated x 16
15x 16
w-
_ x
_x
2" 22 4 B disintegrated ~X
x 4-
3x 4
Ratio of A : B 15x 3x ~ r r : —r- or 16 4 Viscosity
disintegrated _ . 5:4
Benzene-hexachloride exists in eight isomeric forms namely a, P, y, 8, etc. Out of which y-isomer is most active and used as insecticide under the name of gammexane.
is an intensive property.
Peptization is the phenomenon of solution preparation from freshly precipitated substance on adding an electrolyte having common ion to the precipitate. Common ions get adsorbed, impart charge then resultant repulsive interaction causes disintegration.
0
/ P
^0H OH
OI +
..
For NaCl type structure c* = 0.414-0.737 For maximum possible radius of A" ^
= 0.414;
- -
170
0.414
= 410.6
These are isoelectronic species. The greater the nuclear charge, smaller is the size. So, the correct sequence of size is Na+ > Mg2+ > Si4+ > Cl7+ because nuclear charge of Na+ = 11, Mg2+ = 12, Si4* = 14, Cl7+ = 17 C + Oz
C0 2 , AE = - 94 kcal
AE = AEf(C02) - AEy(C) - A£ / (0) 2 = - 94
Applying \Leff = Jn(n + 2), \leff = 5.92 BM is obtained from n = 5. Minimum amount of the electrolyte in millimoles that must be added to one litre of the colloidal sol to bring about complete coagulation or flocculation, thus, the unit of flocculation value is millimole per litre. Cyanide with Grignard reagentforms ketone. /CH3
C=N
O II
[CU(NH3)4]2+ is square planar with one unpaired electron in 4d orbital.
/ \ / \ HO OH HO OH Isophosphoric acid (H 4 P 2 0 6 ) 0 0 II II H-P-O-P-OH I I OH OH Diphosphorous acid (Pyrophosphorous acid, H 4 P 2 0 5 ) 0 0 II II H —P — 0 - P - H I I OH OH Diphosphoric acid (Pyrophosphoric acid, H 4 P 2 0 7 ) 0 0 II II V
base, the acidic character is due to resonance in the acetyl group.
C H 3 - c - N H 2 < — > CH 3 — C = N H 2
Hypophosphoric acid (H 4 P 2 O s ) 0 0
H0^/? OH
O CH3— C — NH 2 behaves as an acid as well as a
C, CH 3 MgBr _
N, + 3H,
2NH,
1 d[ H 2 ] 1 ^[NH 3 ] '2 dt 3 dt
d\N2]. dt d[ H , ] dt
1 rf[NH3 3 dt 1
= 60 x 10" mol L" s-
NMgBr
2 1
48. ( b ) :
OCH, CO — C H ,
./Br \ OH
+ N H 3 + MG: OCH,
Ef(CO,) = - 94 kcal
3
+ 2H20
OCH,
or A E / ( C 0 2 ) - 0 - 0 = - 9 4 , '
An aryl group, due to - I effect is expected to speed up the reaction however, due to resonance it stabilises the reactant veiy much and thus causes net deactivation. Haematite with three molecule of water is called brown haematite i.e., 2Fe 2 0 3 • 3H 2 0. A1203 has high lattice energy and low heat of hydration. It is therefore, insoluble in water. B C H E M I S T R Y TODAY I FEBRUARY '08
West Bengal JEE 2008
Exam on 20th April 2008
The pattern and the syllabus for WB JEE 2008 has been changed. Under the new pattern 80% questions will be multiple choice questions of 1 mark each. 20% questions (short answer type) will carry 2 marks each. INSTRUCTIONS Question paper consists of two sections : Section A contains multiple choice questions. Each question carries 1 mark. Section B contains short answer type questions. Each question carries 2 marks.
Time : 1 hour
SECTION
itpi
A
In buckminster fullerene, each carbon atom is (a) s/?-hybridized (b) ,vp2-hybridized 3 (c) sp -hybridized (d) none of these. CI, hr> A+B
CH 3 CH 2 CH 2 CH 3
(monochlorination products)
The approximate ratio of percentage yields of A and B formed in the above reaction is (a) 50 : 50 (b) 72 : 28 (c) 45 : 55 (d) 60 : 40. In alkaline medium, KMn0 4 reacts as follows: 2KMn0 4 + 2KOH 2K2Mn0 4 + H 2 0 + O. Therefore, the equivalent weight of KMn0 4 will be (a) 31.6 (b) 52.7 (c) 7.0 (d) 158.0 Which of the following cannot be made by using Williamson's Synthesis ? (a) Methoxybenzene (b) Benzyl-p-nitrophenyl ether (c) ferf-Butyl methyl ether (d) Di-terf-butyl ether The product of the following reaction : CH, I
CH, - C - C H - CH, I
(i) Hg(OAc)2, H2C> 2
(ii) NaBH 4
CH,
CH, (a) CH, - C - CH - CH, I I H 3 C OH CH,3 I (b) CH 3 - C - CH 2 - CH 2 OH CH 3 OH I (c) CH 3 - C - CH - CH 2 OH H3C 84
CH,
C H E M I S T R Y TODAY I FEBRUARY '08
2
s
Max. Marks: 50
CH 33 I (d)
HOCH2 - C -
CH2CH3
CH3
A radioisotope has a tm of 10 days. If today 125 g of it is left, what was its weight 40 days earlier? (a) 600 g (b) 1000 g (c) 1250 g (d) 2000 g. Consider the following reaction : RCOO~ Ag + RBr + AgBr + C 0 2 In the statement, this reaction is known as X reaction and proceeds via a Y intermediate.'X' and ' F stand respectively for (a) Hell-Volhard Zelinsky, carbanion (b) Sandmeyer, free radical (c) Wolff, carbene (d) Hunsdiecker, free radical. The conjugate acid of HP0 4 2 ~ is (a) H 3 P0 4 (b) P0 4 3 " (c) H 2 P0 4 " (d) H 3 0 + Consider the isoelectronic series : K+, S 2_ , Cl~ and Ca 2+ , the radii of the ions decreases as (a) Ca 2+ > K + > CI' > S 2 " (b) CI" > S 2 " > K + > Ca 2+ (c) S 2 - > CI" > K + > Ca 2+ (d) K + > C a 2 + > S 2 " > ClWhich of the following are arranged in the decreasing order of dipole moment ? (a) CH3C1, CH 3 Br, CH 3 F (b) CH3C1, CH3F, CH 3 Br (c) CH 3 Br, CH3C1, CH 3 F (d) CH 3 Br, CH3F, CH3C1
If the dissociation constants of two weak acids HAj and HA2 are and K2, then the relative strengths of HA, and HA2 are given by (a)
(b)
(c)
(d)
Friedel-Crafts reaction of benzene with ethylene in presence of HC1 and anhyd. A1C13 gives (a) styrene (b) stilbene (c) ethylbenzene (d) 1,1-diphenylethylene. 23
Na is more stable isotope of Na. Find out the
process by which
Na can undergo radioactive
decay (a) P'-emission (c) (3+- emission
(b) a-emission (d) K-electron capture
The oxidation states of sulphur in the anions of SO32-, S 2 0 4 2 " and S 2 0 6 2 - follows the order: (a) S 2 0 4 2 - < SO, 2 " < S 2 0 6 2 (b) S 0 3 2 - < S 2 0 4 2 " < S 2 0 6 2 (c) S 2 0 4 2 " < S 2 0 6 2 " < SO32(d) S 2 0 6 2 " < S 2 0 4 2 - < S0 3 2 ". Number of g of oxygen in 32.2 g Na 2 S0 4 -10H 2 0 is (a) 20.8 (b) 22.4 (c) 2.24 (d)2.08 Temporary hardness of water is due to the presence of (a) MgS0 4 (b) Mg(HC0 3 ) 2 (c) CaCl 2 (d) CaC0 3 An aqueous solution of 6.3 g of oxalic acid dihydrate is made upto 250 ml. The volume of 0.1 N NaOH required to completely neutralise 10 ml of this solution is (a) 40 ml (b) 20 ml (c) 10 ml (d) 4 ml. Benzene diazonium chloride can be converted into benzene on treatment with (a) H3PO3 (b) H 3 P 0 4 (c) H 3 P 0 2 (d) HPO3. Which of the following is a redox reaction? (a) NaCl + KNO3 N a N 0 3 + KC1 (b) CaC 2 0 4 + 2HC1 CaCl 2 + H 2 C 2 0 4 (c) Mg(OH) 2 + 2NH4C1 MgCl 2 + 2NH 4 OH (d) Zn + 2AgCN 2Ag + Zn(CN) 2 . Which of the following species is paramagnetic?
(b)
(a) 0 2
CN-
(c)
CO
(d) NO+.
Which one of the following reactions is an example for calcination process ? (a) 2Ag + 2HC1 + (O) -> 2AgCl + H 2 0 (b) 2Zn + 0 2 2ZnO (c) 2ZnS + 30 2 2ZnO + 2S0 2 (d) MgC0 3 H> MgO + C 0 2 Sulphonation of phenol with concentrated H 2 S0 4 at 288-293 K gives (a) o-phenolsulphonic acid (b) sulphanilic acid (c) p-phenolsulphonic acid (d) sulphone. Sodium metal is prepared commercially by electrolysis of fused NaCl by (a) Down's process (b) Nelson cell (c) Solvay process (d) Castner and Kellner's cell. The root mean square velocity of one mole of a monoatomic gas having molar volume M is « r m s . The relation between the average kinetic energy (E) of the gas and « r m s is 13 £ 12 E (a) "r. (b) '' \2M "r-ms- = \3M [2E ' i u
(c) u.
(d)
_ r r r.m.s.-^3M
U
Which of the following forms cationic micelles above certain concentration? (a) sodium dodecyl sulphate (b) sodium acetate (c) urea (d) cetyl trimethyl ammonium bromide. In which of the following reactions, addition does not occur according to Markownikov's rule? ROORj (a) CH 3 CH = CH 2 + HC1 ROOR^ CH 2 + HBr (b) C H 3 C H ROORs CH 2 + HI (c) C H 2 CHCH, + HBr ROOR., (d) C H 3 C H van der Waal's equation of state is obeyed by real gases. For n moles of a real gas, the expression will be (a)
P n
na V2 j
(b)
P +
„
a ~2 V2
n-b
(V-b)
= RT = nRT
B C H E M I S T R Y TODAY I FEBRUARY '08
(C)
In the following reaction sequence,
na P + ~T
(nV-b)
= nRT
CuCN/pyridine 6
(d)
P_ +
n2a | \(V-nb)
^
V
o
(b)
^ C H ==N O H
O (d) O
(c) O
O
o
o
When equal volumes of the following solutions are mixed, precipitation of AgCl (Ksp = l-8xlO" 10 ) will occur only with (a) IO"4 M Ag + and 10" 4 M CI (b) IO"5 M Ag + and 10~5 M Cl" (c) 10"6 M Ag + and IO"6 M Cl" (d) IO-10 M Ag + and IO"10 M Cl~ At constant temperature, the equilibrium constant (Kp) for the decomposition reaction s N204 v 2 N 0 2 is expressed by 2 Kp = (4x P)/( 1 - x2) where P = pressure, x = extent of decomposition. Which one of the following statements is true? (a) Kp increases with increase of P (b) Kp decreases with increase of x (c) Kp increases with decrease of x (d) Kp remains constant with change in P and x. Which of the following will be most readily dehydrated in acidic conditions ? O
OH
(a)
OH (b)
o
O (d)
(c) OH
dU. H 2 SQ 4 *
(b) benzene (d) benzamide.
Which of the following compound is not known? (a) NC13 (b) NI3 (c) NC15 (d) SbCl3. Among K 0 2 , A10 2 ", B a 0 2 and N 0 2 + , unpaired electron is present in (a) N 0 2 + and B a 0 2 (b) KO z and A102~ (c) K 0 2 only (d) B a 0 2 only. A drag that is antipyretic as well as analgesic is (a) Chloropromazine hydrochloride (b) para - Acetamidophenol (c) Chloroquin (d) Penicillin Which of the following salts is colourless? (a) CdCl2 (b) CuS0 4 -5H 2 0 (c) MnS0 4 -7H 2 0 (d) NiS0 4 -7H 2 0. In DNA, the complementary bases are (a) Uracil and adenine : cytosine and guanine (b) Adenine and thymine : guanine and cytosine (c) Adenine and thymine: guanine and uracil (d) Adenine and guanine : thymine and cytosine. The group reagent for third group is NH 4 OH in presence of (a) (NH 4 ) 2 C0 3 (b) NaCl (c) (NH 4 ) 2 S0 4 (d) NH4C1. In nucleic acids, the sequence is (a) Phosphate-Base-Sugar (b) Sugar-Base-Phosphate (c) Base-Sugar-Phosphate (d) Base-Phosphate-Sugar SECTION - B
OH
The electron affinities of halogens are : F = 332, CI = 349, Br = 324, I = 295 kJ mol" 1 . The higher value for CI as compared to that of F is due to (a) higher atomic radius of F (b) smaller electronegativity of F (c) weaker electron-electron repulsion in CI (d) more vacant p-subshell in CI.
B C H E M I S T R Y TODAY I FEBRUARY '08
523 K
The product Y is (a) benzonitrile (c) benzoic acid
= nRT
Tautomerism is not exhibited by (a) Q
5
Pure aniline is colourless, but when kept exposed in air it becomes coloured. Why? How can you obtain colourless aniline from it? Glacial acetic acid is treated with acetylene gas in presence of HgS0 4 and the resultant product is distilled. Explain why ? When a hydrogen bond is symbolised by X—H — Y, what do the solid and dotted lines represent? Which distance is shorter?
Write a plausible Lewis structure for the chlorite ion, C102~. Show the formal charges on each atom and the net charge. Identify redox reaction(s) and the reducing and oxidising agent(s) from the following reactions: (i) 2Mn0 4 " + 5S0 2 + 6H 2 0 ->• 5S0 4 2 - + 2Mn2+ + 4H 3 0 + + 3 (ii) NH4 + P0 4 NH 3 + HP0 4 2 " (iii) HCIO + H2S
H 3 0 + + CI" + S
Write, with equation, what happens when
2KMn0 4 = O 2(158)
Di-?er?-butyl ether cannot be made by Williamson's synthesis, since f-alkyl halides prefer to undergo elimination rather than substitution, i.e., CH, CH, I I CH33 - C - Br + CH33 - C - 0~Na + |
How can you distinguish (i) Formaldehyde and acetaldehyde (ii) Methyl alcohol and ethyl alcohol Explain and exemplify (i) Haloform reaction (ii) Cannizzaro reaction. Find the number of covalent bonds in C 2 H 4 0 2 . How can you explain the formation of (i) NH4+ from NH 3 and (ii) BH4" from BH3. (i) Which bond has greater ionic character: H - F or H - CI? Give reason. (ii) The boiling point of NH 3 is greater than that of HC1. How can you account for this? SOLUTIONS In buckminster fullerene (Bucky ball, C 60 ) each carbon atom is sp2 hybridised giving a spherical shape resembling to a soccer ball. H-Butane has two types of H-atoms (six 1° and four 2°), therefore, it gives two monochloroderivatives, i.e., 2-chlorobutane (A) and 1-chlorobutane (B). Their relative percentage yields are Amount of A _ 4 Amount of B ~ 6
3.8 _ 15.2 _ 72% 1.0 ~ 6.0 ~ 28%'
|
CH3
Sodium sulphate is heated strongly with carbon and the residue is made to react with an aqueous solution of zinc sulphate. Sodium aluminate solution is heated with ammonium chloride. An aqueous solution of potassium iodide in which chloroform has been added is shaken gradually with chlorine water in excess. A mixed solution of sodium nitrate and caustic soda is heated with aluminium powder. Fluorine reacts with cold dilute solution of caustic soda.
16 parts
8 parts of O = 158 parts of KMn0 4 Hence eq. wt. = 158.
CH3
— >
-NaBr
CH3
CH3
I
I
CH3 - c = CH2 + CH3C - OH CH3
Oxymercuration-reduction follows Markownikov's rule. Thus CH3 I C H
Hg(OAc)2, H 2 Q
3 - c - CH
CH2
( M a r k o w n j k o v ' s addition)"*
CH3
CHo I
NaBH 4
CH, - C - CH - CH, I I I H 3 C OH HgOAc N = | G = 4,
or
CHo I
> CH, - C - CH - CH,3 I I H 3 c OH
125 G = ^ [ A O ]
[A0] = 2000 g
Hunsdiecker reaction occurs by a free radical intermediate. HP0 4 2 " + H+ ;
H 2 P0 4 .
Amongst isoelectronic ions, ionic, radii of anions is more than that of cations. Further size of the anion increases with increase in -ve charge and size of cation decreases with increase in +ve charge. CH3C1, CH3F, CH3Br. Strength of HA,/strength of HA2 = ^ K J K 2 . C H 2 = C H 2 + HC1 + A1C13 CH3CH2+A1C14" CH3CH2 + C6H6
CH3CH2C6H5 ethylbenzene
2
f N a —£-»
23
Na
S 2 0 4 2 - (+3) < S0 3 2 " (+4) < S 2 0 6 2 " (+5) 1 mol Na 2 S0 4 • 10H 2 0 = 14 g atoms of (O) B C H E M I S T R Y TODAY I FEBRUARY '08
i.e. 322 g Na 2 S0 4 • 10H 2 0 contain (O) = 224 g.
does not exhibit tautomerism. After mixing, [Ag+] [Cl~] > Ksp only for (a).
Ca and Mg-bicarbonates cause temporary hardness to water. Normality of oxalic acid sol 6.3 1000 n A 1 > J x = 0.4 N 250 63 10 x 0.4 = V x 0.1 or, V = 40 ml =
Benzene diazonium salts on reduction with H 3 P0 2 in presence of Cu + ions gives benzene. C 6 H 5 N 2 C1 + H 3 P0 2 + H 2 O C u > C 6 H 6 + N 2 + HCl + H3PO3 Oxidation
Zn +
-> Zn 2+ + 2e- ;
Reduction
Ag + e-
Aldols, i.e., (3-hydroxyaldehydes or (3-hydroxyketones readily undergo dehydration to form a , P-unsaturated aldehydes or ketones. O
OH
+
P-Hydroxy ketone
H
OH, „+
u n
QH.CN
[C6H5(OH):3J
In calcination, carbonates are decomposed to C0 2 . At 288-293 K, sulphonation is kinetically controlled and hence o-phenolsulphonic acid is formed. Na metal is obtained by Down's process by electrolysis of fused NaCl. R.M.S. of one mole of monoatomic gas is 3 RT M
O
H
523 K
> Ag
Average kinetic energy is E = ^RT
O
C6H5Br C u C N W ^
0 2 contains one unpaired electron.
=
Kp is constant at constant temperature.
(unstable)
2
boil
C6H5COOH benzoic acid
NC15, due to non availability of d-orbitals in case of nitrogen, is not known. K
+
nq-o:]
p-Acetamidophenol. CdCl 2 has Cd 2+ ion (4d10) which is colourless. In DNA, adenine faces thymine and guanine faces cytosine. The group reagent for third group is NH 4 OH in presence of NH4C1. Base—Sugar—Phosphate.
or, 2E = 3RT.
"r.m.s = ^ M[M • Cetyl trimethyl ammonium cations aggregate to form cationic micelles. In presence of peroxides, only the addition of HBr to unsymmetrical alkenes does not occur according to Markownikov's rule. Since alkene (b) is unsymmetrical while alkene (d) is symmetrical, therefore, the correct answer is alkene (b). van der Waal's equation is 2' p I an + V2 ' (V - nb) = n RT Essential condition for tautomerism is the presence of an a-hydrogen on a saturated carbon attached to C = O, NO, N0 2 , etc. or should have a H-atom present on a heteroatom (O, N, S, etc.) attached to a double bond. Thus, option (a) does not have a a-hydrogen on a saturated carbon and hence B C H E M I S T R Y TODAY I FEBRUARY '08
Aniline is easily oxidised by oxygen of air in presence of light giving first a light brown and then a deep brcwn colour. The presence of a lone pair of electron on the nitrogen atom makes it susceptible to oxidation by air. Colourless aniline can be obtained from this dark coloured one by distillation. When glacial acetic acid is treated with acetylene gas in presence of mercuric sulphate, ethylene diacetate is formed when the mixture is distilled, it decomposes into acetic anhydride and acetaldehyde when the latter escapes first due to its much lower boiling point. Solid line represents an ordinary chemical bond (o-bond, covalent bond) and the dotted line represents a hydrogen bond. The distance between X - H is shorter than the distance between H - Y. Lewis dot structure of chlorite ion can be written as: :0: CI :0:
Formal charges are: O (-1), CI (+ 1) and O ( - 1) Net charge is ( - 1 + 1 - 1) i.e., - 1. (i) Redox reaction, Mn0 4 _ is oxidising agent and S0 2 is the reducing agent. (ii) Acid-base reaction. (iii) Redox reaction. HCIO is the oxidising agent and H 2 S is the reducing agent. When sodium sulphate is heated strongly with carbon, it is reduced to sodium sulphide. Na 2 S0 4 + 4C Na 2 S + 4CO When the residue is heated with zinc sulphate solution, white zinc sulphide is precipitated Na 2 S + ZnS0 4 -H> Na 2 S0 4 + ZnS When sodium aluminate solution is heated with ammonium chloride, white gelatinous aluminium hydroxide is precipitated and ammonia gas is given off. NaA10 2 + NH 4 CI + H 2 0->A1(0H) 3 + NaCl + NH 3 Chlorine liberates iodine from potassium iodide which goes into chloroform layer colouring it violet. 2KI + Cl2 -> 2KC1 + I 2 Aluminium powder reacts with caustic soda solution liberating nascent hydrogen which reduces sodium nitrate solution giving off pungent smelling ammonia gas. NaOH + Al + H 2 0 H> NaA10 2 + 3 [H] NaN0 3 + 8 [H] NaOH + 2H 2 0 + NH 3 Over all reactions is: 5NaOH + 8A1 + 3NaN0 3 +2H 2 0 -> 8NaA102 + 3NH3 Fluorine reacts with cold dilute solution of caustic soda giving sodium fluoride, oxygen fluoride and water. 2F 2 + 2NaOH 2NaF + 0 F 2 + H 2 0 (i) When warmed with I 2 and NaOH solution, acetaldehyde gives yellow precipitate of iodoform with characteristic smell. Formaldehyde does not give iodoform. (ii) When warmed with I 2 and NaOH soln., ethyl alcohol gives yellow precipitate of iodoform with characteristic smell. Methyl alcohol does not respond to this test. (i) Ethanol, CH3CH2OH, acetaldehyde, CH3CHO, ketones having the formula RCOCH 3 and secondary alcohol of the type RCH (OH) CH 3 reacts with halogen in presence of aqueous NaOH or KOH to give haloform. These reactions are classified as haloform reaction, e.g.
CH3COCH3 I2 + N a O H > CHI 3 + CH 3 COONa CH 3 CH 2 OH c12 + k o h > CHC13 + HCOOK (ii) Aldehydes having no a-hydrogen atom reacts with concentrated aqueous solution of caustic alkalies to give alcohol and salt of acid by self-oxidation reduction. 2HCHO + NaOH CHO
CH 3 OH + HCOONa CH2OH
2(Q]+NaOH
> (Q)
cOONa +
( Q }
Number of covalent bonds in C 2 H 4 0 2 H O I 11 H-C-C-0-His8. I H (i) In the formation of NH 4 + , the lone pair of electron on the nitrogen atom of ammonia molecule is donated to a proton, H + which requires two electrons for its stability. H
H
H - N = +H 4 " > H — N ->H + I I H H (i) In the formation of BH4~, electron pairs of H" ion is shared with boron atom in BH 3 which has only six electrons and requires two more electrons for its stability. H H- B- H+ >R - B H" l I H H In both cases, co-ordinate covalent bonds are formed. (i) Fluorine is more electronegative than chlorine. So the electronegativity difference between hydrogen and fluorine is more than that between hydrogen and chlorine. So HF has greater ionic character than H - CI. (ii) Though the electronegativity of chlorine is equal to that of nitrogen, hydrogen bonding in ammonia is of much higher degree than that in hydrogen chloride due to much larger size of chlorine atom. So association due to hydrogen bonding in ammonia is appreciable while this is negligible in hydrogen chloride and ammonia has greater boiling point than hydrogen chloride. B C H E M I S T R Y TODAY I FEBRUARY '08
Objective Problems IsIBnillaEMIUI* (d)
O CH, - CH—CH - O - C
l.
NaOH,(aq)
Col
>(A) + (B)
/CH3 CH, - C=C. \ O-C CH, o NaOH,« > ( Q + (5)
Me Me
(B) on hydrolysis gives dicarboxylic acid.
3. In which of the following pairs both reactions is/are spontaneous ? (a) (i) ROH + NaNH2—• (ii) PhOH + NaHC0 3 (b) (i) RCOOH + NaHC0 3 ->• (ii) PhOH + NaOH—> (c) (i) ROH + RLi -»(ii) PhOH + NaNH 2 -> (d) (i) RCOOH + N a O H ^ (ii) ROH + NaHC0 3 - » 4.
Both (A) and (Q can react with 2, 4-DNPH. (A) and ( Q can be distinguished by reagent R. R and (B)
• ( A )
(i)[Z3(ii)H + ->(Q,
M g / e t h e r
>
( B )
(Q is
are:
(a)
(b)
(c)
(d)
(a) Fehling's solution, Me -^Q^)—COONa (b) I2/KOH, Me - < Q > - C O O H C 0 0 N a
(c) AgN0 3 - NH4OH, Me (d) PhNHNH 2 , Me ^ Q )
- C O O N a
pH = x, at which rate is maximum
-NH2OH-
(A)
O
PCI,
MB)
5. Which of the following order is/are correct ? (a) H 2 C0 3 > H 2 0 > PhOH > ROH > CH = CH (acid strength) (b) CF3COCF3 > CCl3CHO > CH 3 CHO > HCHO (nucleophilic addition reactivity) CH2OH CH2OH CH(OH)CH3 CH(OH)CH3
(§} (B) as major alkene Which of the following is/are correct? (a) (A) and (B) are geometrical isomers of each other. (b) The heat of hydrogenation of (A) is numerically smaller than that of (B) (c) (A) on treatment with Br2/CCl4 gives meso product. (d) (5) on treatment with Baeyer's reagent gives racemic mixture. 8. In column (A), a reaction is given and in column (B), the information is given regarding the product (or major product) formed in the reaction given in column (A). Match in appropriate manner. Column (A) (i) CH2 = CH2 + CO + H2
Co,(CO)g
(ii) Me 2 C = CH2 + CO + H 2 0 (iii) MeCH 2 CH = CH2
V
H 3 PO 4 :
>
(i)B2H6(ii)H20, (i)Hg(0Ac) 2 ,H 2 0 (ii) NaBH 4 , NaOH
(iv)Me3C - C H = CH2 Column (B) (p) reduces Fehling's solution (q) produces C0 2 from NaHC0 3 (r) gives yellow ppt. with I2/OH (s) gives red colour in Victor Meyer test (t) gives blue colour in Victor Meyer test (u) liberates H 2 by reacting with Na metal 9. In which of the following reactions the product shown is major of that reaction? (a)
18
'H
(b)
NNHCONH,
+ CH3CH2OH CH.
dry HC1 .
OEt Me
6
CHEMISTRY TODAY JANUARY '08
dil OH"
OH
CHO
D (d)
alc. KOH/heat
(a) due to reaction there is no change in O.N. of S (b) the product on treatment with NaOH gives Na 2 S0 4 as an inorganic product (c) The number of sp3 hybridised atoms in the product are 5 (don't consider those oxygens which are covalently bonded to just one atom.) (d) The product on treatment with HC1 produces S0 2 gas. Comprehension Sodium or potassium salt of carboxylic acid on electrolysis produces hydrocarbon and C0 2 at one electrode and H2 gas at other electrode. The reaction mechanism involves free radicals. (A) is a dicarboxylic acid. The aqueous solution of potassium salt of (A) on electrolysis gives (B)(g) and (C)fe) at one electrode and H 2 at another electrode. (B) on treatment with HC1 gives (D) via intermediate (J). (D) on treatment with Mg - ether followed by reaction with (C) and then hydrolysis gives an acid (E). The calcium salt of (E) on heating gives an inorganic salt (F) along with organic compound (G). (G) is lowest ketone C„H2nO which cannot perform haloform reaction. ( H ) is higher homologue of (A). The calcium salt of (H) on heating gives (J) along with (F). Answer the following questions : 12. (7) is more stable than (a) CH2 = CH + (c) CH 3 CH 2 CH 2 +
(b) (d)
CH3+ Ph+
13. The aqueous solution of sodium salt of (E) on electrolysis gives.
(a) an alkane, (B) and C 0 2 at anode (b) an alkane which on vapour phase nitration gives a mixture of six nitro alkanes (c) an ester which on Bouveault - Blanc reduction gives just one alcohol. (d) an alkane which on chlorination gives a mixture of two isomeric dichlorides. 14. Which of the following is/are correct for (F)l (a) (F) is thermally more stable than MgC0 3 (b) (F) has greater Ksp than SrC0 3 (c)
(i) heat (ii) carbon (iii) hydrolysis 3metfaape
{F)
(d) (F) + dil HCl —» greenish yellow coloured gas. Ph3P = CH,
1 J . (J)
conc. H,SO,/heat
—
>
B 2 H 6 /THF
>
H 2 0 2 /Na0H
>
>(K)
H1/redp
(H) > straight chain alkane (L). Which of the following is/are correct for (K)l (a) (K) on oxidative ozonolysis gives (H) (b) (K) on reaction with CH 2 N 2 /^u gives a bicyclo alkane of formula C 6 H 10 (c) (K) on reaction with CH2/N2//zu gives a spiro alkane of formula C 6 H| 0 (d) (K) on reaction with CH2N2/7zu gives a cyclo alkane of formular C6H12.
2. (a) Si'gMy acidic mediun^
+ NH OH
o
N, OH
PCL
{B)
hydro'y^'S NH2(CH2)4COOH
3. (b),(e) (A) ROH is stronger acid than NH 3 therefore ROH + NaNH 2 RONa + NH 3 is spontaneous. (B) PhOH(WA) + NaHC0 3 -> PhONa + H2C03(S.A) non-spontaneous. ( Q RCOOH(SA)+NaHC0 3 -> RC00Na+H 2 C0 3 (WA) spontaneous. (D)PhOH(SA) + NaOH PhONa + HzO(WA) spontaneous. (E) ROH(SA) + RLi ROLi + RH(WA) spontaneous. (F) PhOH(SA) + NaNH, -> PhONa + NH 3 (WA) spontaneous. (G)RCOOH(SA) + NaOH RCOONa + H 2 0(WA) spontaneous. (H)ROH(WA) + NaHC0 3 RONa + H 2 C0 3 (SA) non-spontaneous. 4. (c)
SOLUTION
-Br -Br
!CBr, H Me3C - O-
• CH, - CH=:CH - O - cC
Coj
(A)
-Br -Br
^NaOH,
Me3COH-
Me CH,-CH=CH-OH
CH2 - CH2CHO (A)
(A)
Similarly: •H,
.CH3 CH2-CH-C (Q
CH
3
M&/ether
PhMgBr +
> PhMgBr (B)
CH2 - CH2 CH2-O
-> Ph(CH2)3OMgBr
0
• Ph(CH,)3OH B CHEMISTRY TODAYIFEBRUARY'08
9. (b),(d) UVJJ ^ ^
HO
k^^J
CH,2
CH. CHx r
^CH2
kJ
1-CH,
(a) -H
+
.
(b) (Q
5. (c), (d) Correct orders are : H 2 C0 3 > PhOH > H 2 0 > ROH > CH = CH (acid strength) CF 3 COCF 3 > CCl 3 CHO > HCHO > CH 3 CH0 (nucleophilic addition) CH 2
CH 2
CHCH 3
J NO, 2
6. (a), (b), (d) (i) Peroxide effect is not applicable in case of addition o f H C l a n d H I (ii) The reaction of alkene with NBS proceeds through attack of Br' at allylic C - H bond. 7. (b), (c), (d) Cri^
CH3CH2CHFCH3 alc- K O H / h e a t > CH3CH2CH— CH2
H
H
(A)
(B)
Me Br2/CCl4(antiadditionj H - ^ - B r ( m e s o . p r o d u c t )
^ME
C H 3 C H 2 C H = CH,
M E K
KMNO
>
8. (i) CH, = CH2 + CO + H2
\
/
(C)
(stability of carbocation)
Me J f
nrrr OCH,
CH 3 CH;CH(OH)CH 2 OH
(racemic mixture) Co2 (C0)8 * CH 3 CH 2 CHO (p) only
H
v 33 C - CH = CHz2 (iv)Me ' demercuration
Me 3 C - CHOH - CH3 (r), (t), (u) Ans. (i)-(p); (ii)-(q), (u); (iiiHs), (u); (ivHr),(t),(u) B CHEMISTRY TODAY I FEBRUARY '08
pCH 3
OCH,
/
ii+
\
Et H
I
CH
CH, •0=C
CH CFL
CH,
D (d) H
/)Me
OH
CH3 H t I 0 = C — C H , CH, C^
CH, CEL2
/ CH,
anti elimination/-DCl
//
H CI
Me (i)
-NH, (3) 10. (a) "OOC - CH2CH2 - CH„ -COOKb (1) = 2; K„ (3 )=y=* pK„ $)=>Kb (2) = x => pKb (2) => - log x pK(2) + pKa(3) Pl = _ (14 + logx) + (14 + logy)
=
log y
14 +
l o g V
^
11. (a), (c), (d) CH3 CH 2 CH = O + NaHS0 3 - » OH
CH3CH2CH
Me,CH - COOH (q), (u) WWiQHA,
\
>
O CH
(ii) Me2C = CH2 + CO + H 2 0 — — ^
MeCH 2 CH 2 CH 2 OH (s), (u)
r OCH,
CH2CH3
H , 2P O 4
(iii)MeCH2CH = CH2
/
\
A
CH, —
H
/
OCH,<
CHCH 3
:o>ro>ro>ro.
CH3CH2CHBrCH3 alc. KOH/heat
\
CH 3 CH 2 CH;
-OH
+ NaOH
ONa O'
'O
~S03Na CH 3 CH 2 CH = O + Na 2 S0 3 + H 2 0 -OH + HC1 —¥ CH 3 CH 2 CH; -S0 3 Na CH 3 CH 2 CHO + NaCl + S0 2 + H 2 0 O. N of S in each case is +4.
Comprehension :
2 R C O O N a -> 2RCOO" + 2Na +
A t cathode : 2 H 2 0 + 2e A t anode : 2RCOO" 2RCOO* 2R-
N 0 2 + CH 3 CH 2 *CH(N0 2 )CH 3 + CH 3 CH 2 CH 2 - NO 2 + CH 3 - NO 2 + CH 3 CH 2 - NO 2
2 R C O O ' + 2e
2R' + 2 C 0 2
coupling » R - R:
Disproportionation
2R
CH 3 CH 2 COOCH,CH 3 >R - H +
alkene The products are R - R , R - H , alkene and ester R C O O R .
(A)
(B)
is C H 2 - C H 2
is C H 2 = C H , ,
(C) is
C02
CH,CH,CH,OH+CH,CH,OH
» CH 3 CHC1 2 + C1CH 2 CH 2 C1
14. (a), (b) : The thermodynamic stability of alkaline earth metal carbonates follows the order B e C 0 3 < M g C 0 3 < CaC0 3 < SrC0 3 < B a C 0 3 B e C 0 3 > M g C 0 3 > C a C 0 3 > SrC0 3 > B a C 0 3
(D) is CH 3 CH 2 C1, (£) is C H 3 C H 2 C O O H ,
CaC0 3
(F) is CaC0 3 , (G) is C H 3 C H 2 C O C H , C H 3
CaO + C0 2 ; CaO + 3C -> CaC 2 + C O
CaC, + 2 H 2 0
CH, - C O O H
C 2 H 2 + Ca(OH) 2
CaC0 3 + dil 2HC1 -> CaCl 2 + C 0 2 + H 2 0
(I) is C H 3 C H 2 CH,
CH3CHJ
Na/alc. ,
chlorination
The Ksp order is
COOH COOH
(B) is CH,
vapour phase nitration
CH3CH,CH,CH3
H 2 + 2GII
15. (a), (b)
COOH
/O
(J) is
12. (a), (b), (d); 13. (a), (b), (d) electrolysis CH3CH2COONaw-
^ CH-, — C O O H 2 (H) C H , ^
- Na+at anode.
ttt / J n
HI/redP
?
«-pentane (Z)
C H 3 C H 2 C O O - -> C H 3 C H 2 C O O + e CH3CH2COO'
CH 3 CH 2 '+ C 0 2
So the products at anode 3ie CH3CH2— CH2CH3
(K) |
CH 3 CH 2 - H, CH 2 = CH 2 , C H 3 C H 2 C O O C H 2 C H 3
11 + CH2N2
WUt/G-
A TEXT BOOK OF mm
| H » m p K II'.
1
I
Based on latest pattern of AIEEE/IIT and PMT's 1 The book is represented in such a way that each student would be able to solve any problem of Engineering as well as Medical Entrance Exam Book covers complete syllabus in the form of concise text • Improve your problem solving skills with CHECK YOUR CONCEPT boxes * Presentation makes Organic Chemistry interesting and easy * MCQ's of 3 different levels - Concept based, standard, numerical based with detailed solutions A number of objective and subjective problems to enhance problem solving approach.
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P r o b l e m s in Organic Chemistry Nicotine is an alkaloidfound in the nightshade family of plants (Solanaceae), predominantly in tobacco, and in lower quantities in tomato, potato, eggplant (aubergine), and green pepper. Nicotine alkaloids are also found in the leaves of the coca plant. Nicotine has been found to constitute approximately 0.6 - 3% of dry weight of tobacco. X are (a) (b) (c) (d)
CI,
Benzotrichloride
Hydrolysis
> Y . X and Y
C6H6, C6H5CHO C 6 H 5 CH 3 , C 6 H 5 C H O C6H5ch3, C6HSCOOH
C6H6, C 6 H 5 C O O H
2. Cyclic hydrocarbon molecule, A has all the carbons and hydrogens in a single plane. All the carboncarbon bonds are of same length and less than 1.54 A and more than 1.34 A . The C - C - C bond angle will be (approx). (a) 120° (b) 180° (c) 100° (d) 109°28' The major product (70 - 80%) of the reaction between /w-dinitrobenzenc and (NH4)2SX is NO, NH, (a)
0 , N ^ N 0
2
(b)
NH,
(c) H 2 N
NO, NH,
NH,
(d)
NH, HS Under ordinary conditions nucleophilic substitution is not possible in benzene ring of aryl halides, why? (a) C - X bond in aryl halides is stable due to derealization of electrons by resonance. (b) C - X b o n d possess a double bond character. (c) C - if bond is stronger in aryl halides than C - X bond in alkyl halides, due to resonance. (d) All the above.
Compound (A) C3H6C12 on reaction with alkali gives (.B) C 3 H 6 0 or (C) C 3 H 4 . (B) on vigorous oxidation gave a compound C 3 H 6 0 2 . C with dilute H 2 S0 4 containing Hg 2+ ion gave (D) C 3 H 6 0, which with
bromine and alkali gave the sodium salt of C 2 H 4 0 2 . A is (a) CH 3 CH 2 CHC1 2 (b) CH3CC12CH3 (c) CH2C1CH2CH2C1 (d) CH3CHC1CH,C1 6. An aromatic amine (A) was treated with alcoholic potash and another compound (Y), a foul smelling product was formed with formula C 6 H 5 NC. (J) was formed by reacting a compound (Z) with Cl2 in the presence of slaked lime. The compound (Z) is (a) C 6 H 5 NH 2 (b) C 2 H 5 OH (c) CH 3 OCH 3 (d) CHC13 Arrange the following compounds in order of ease of dehydrohalogenation by alcoholic KOH solution. •-Br ^ ^ B r
0Br
M [5] (a) A < B < C < D (c) A < B < D < C
[C] (b) (d)
QE
[D] A WFFC«-cateintn T>> £»PCRT"
•
The' Essential Resoufc* for Aspiting Oocton
with
B C H E M I S T R Y T O D A Y I FEBRUARY '08
.
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C 6 H 5 OH < CH 3 COOH < CCljCOOH < C 6 H 5 SO 3 H 10 4.79 0.9 -2.6 Stronger the acid, weaker is the conjugate base and thus better is the leaving group. Hence leaving tendency of the conjugate base is All the statements mentioned here are correct. Presence of /-butyl and - N O , in close vicinity in compound (II) makes - N 0 2 loose its planarity with benzene ring and - M effect is not shown by that group. So, in (I) there is -I, - M effect of - N O , group whereas in (II) there is only - I effect.
) and
AIIMS
CBSE
DPMT
VMMC
EAMCET
,
According tonewpattem
D v a r l l # > A 1 r i O O - I C C
WmSHKmSmm-' MP-PMT
AFMC
MG1MS
PMDT Bihar PMT Haryana Kerala PMT j
Raj. PMT
TNPCEE
50 MCQs are given in this Practice Paper. Choose the most appropriate option. Answers are provided at the end of the paper. The reaction of NaCl and K 2 Cr 2 0 7 mixture with concentrated H 2 S0 4 result in (a) Colourless gas (b) Violet coloured gas (c) Deep red gas (d) No gas formation
1.
Styphnic acid is (a) 2,4,6-Trinitrophenol (b) 2,4,6-Trinitroresorcinol (c) 2,4-Dinitroresorcinol (d) Phloroglucinol
2.
When 0.5 g of sulphur is burnt to S 0 2 4.6 kJ of heat is liberated. What is the enthalpy of formation of sulphur dioxide ? (S = 32 and O = 16) (a) +147.2 kJ (b) -147.2 kJ (c) -294.4 kJ (d) +294.4 kJ
10. The IUPAC name of the compound
3.
Assuming complete ionisation, the pH of 0.1 M HCl is 1. The molarity of H 2 S0 4 with the same pH is (a) 0.2 (b) 0.1 (c) 2.0 (d) 0.05
11. If n and I are respectively the principle and azimuthal quantum numbers, then the expression for calculating the total number of electrons in any energy level is
4.
Conversion of CH 4 to CH3C1 is an example of .... reaction (a) electrophilic substitution (b) nucleophilic substitution (c) free radical substitution (d) free radical addition
5.
In a sample of pure compound Na = 0.0887 mole O = 0.132 mole C = 2.65 x 1022 atoms The empirical formula of the compound is (a) Na 2 C0 3 (b) Na 3 0 2 C 5 (c) Na 0 0887 O 0 .i3 2 C 2 . 6 5
x
io22
(d) NaCO Which of the following compound has co-ordinate bond ? (a) NH4C1 (b) A1C13 (c) NaCl (d) Cl 2
7.
The tautomerism is exhibited by
8.
(b) (d)
(CH3)3CNO R-CH2-NO
The mixture used in Holme's signals is (a) CaC, + CaCl 2 (b) CaC 2 + Ca 3 P 2 (c) CaCl 2 + Ca 3 P 3 (d) CaC 2 + Ca 3 N 2
62
CHEMISTRY TODAY IFEBRUARY'08
(a)
Bicyclo [2.1.0] pentane 1, 2-Cyclopropyl cyclobutane Cyclopentane [4.3] azulene 1, 2-Methylene cyclobutane.
1 2 ( 2 1 + 1) 1=0
(b)
'~i 1 2(.2l +1)
l = n+l
(c)
I 2(21 + 1) ;=0
(d) v '
1=0
'2(27 + 1)
12. The colour of the precipitate produced by adding NaOH solution to HgCl 2 is (a) yellow (b) black (c) brown (d) white 13. What happens when KI is heated with conc. H 2 S0 4 ? (a) KI3 is formed (b) Only I 2 is liberated (c) I 2 and S0 2 are liberated (d) None of these
6.
(a) R 3 C N 0 2 (c) ( C H 3 ) 2 N H
(a) (b) (c) (d)
is
2
14. Addition of methanol to 2-methylpropene in the presence of conc.H 2 SG 4 gives (a) tert-Butyl alcohol (b) tert-Butyl methyl ether (c) Di-fert-butyl ether (d) Dimethyl ether 15. In an electrolysis of metallic chloride 3.283 g of metal (molar mass = 197 g mol ') was deposited on the cathode by the passage of 4825 C of electric charge. The charge number of metal ion is (a) 0.5 (b) 1.0 (c) 2.0 (d) 3.0
16. Acetone and acetophenone can be distinguished by (a) DNP test (b) Tollen's test (c) Saturated solution of NaHS0 3 (d) Schiff's reagent 17. In the chain reaction, 238
1
1
92U
+ Qn—^Nuclide A + Nuclide B + 3Qn + Energy E neutrons and energy produced at the (n - l) th step will be (a) 3 n , n E (b) 3n~\ 3n'2E l (c) 3", 3 — E (d) none of these 18. An aqueous solution containing 100 g of dissolved M g S 0 4 is fed to a crystallizer where 80% of the dissolved salt crystallises out as M g S 0 4 - 6 H 2 0 crystals. How many gram of the hexahydrate salt crystals are obtained from the crystallizer ? (Given Mg = 24; S = 32; O = 16 and H = 1) (a) 152 (b) 80 (c) 100 (d) 120 .
Me
Me
H
Hydrogenation atom of the above compound in the presence of poisoned palladium catalyst gives (a) optically active compound (b) an optically inactive compound (c) a racemic mixture (d) a diastereomeric mixture 20. Which of the following is incorrect statement ? (a) Flourine does not form oxyacids (b) C1 2 0 7 is an anhydride of perchloric acid (c) IC1 is a good conductor of electricity in fused state (d) Melting and boiling points of HBr are less than those of HC1 21. When primary amine is heated with CS 2 in presence of excess mercuric chloride, it gives iso-thiocyanate. This reaction is called (a) Hofmann-bromamide reaction (b) Hofmann mustard oil reaction (c) Carbylamine reaction (d) Perkin reaction 22. [Fe(CN6)]3~ and [Fe(H 2 0) 6 ] 3+ show the hybridisation states respectively (a) sp3cf and (fsp3 (b) cPsp3 and sp3cP (c) both (a) and (b) (d) none of these 23. The geometry of IC12" ions is (a) trigonal with sp2 hybridisation
(b) tetrahedral with sp3 hybridisation (c) square planar with dsp2 hybridisation (d) trigonal bipyramidal with sp3d hybridisation 24. The most efficient agent for the absorption of S 0 3 is (a) 98% H 2 S0 4 (b) 80% H 2 S0 4 (c) 20% oleum (d) 90% H 2 S0 4 25. Which of the following has highest chlorine content ? (a) Pyrene (b) DDT (c) Chloral (d) Gammaxane 26. Which one of the following cation does not form an amine complex ? (a) Ag + (b) Cu 2+ 2+ (c) Cd (d) Na + 27. The radius of hydrogen atom in the ground state is 0.53 A. The radius of Li + ion (atomic number = 3) in a similar state is (a)
1.06 A
(b)
0.265 A
(c)
0.17
A
(d)
0.53
A
28. KI on treatment with CuS0 4 solution gives (a) K 2 S0 4 + Cul 2 (b) K 2 S0 4 + Cu 4 I 4 (c) K 2 S0 4 + Cul 2 + I 2 (d) K 2 S0 4 + Cul + I2 29. The total number of valence electrons in 4.2 gm of N 3 " ion is (where, NA is the avogadro's number) (a) 2 . 1 A^ (b) 4 . 2 NA (c) 1.8 NA (d) 3 . 2 NA 30. Ammonia form complexes with Ag + according to the following reactions : (i) [Ag(H 2 0) 2 r + NH 3{fl9) = = = ^ [Ag(NH 3 )(H 2 0 (a9) )] + + H 2 0 ( O (ii) [Ag(NH 3 )(H 2 0 ( a ? ) )r + NH 3(a?) [Ag(NH3)2(A9)R + H2OI()
The equilibrium constants of equilibrium (i) and (ii) are 2.0 x 10 3 and 8.3 x 10 3 respectively. The equilibrium constant of the following reaction [Ag(H20)2(fl?1]+ + 2NH3(A9)
(a) 4.15 (c) 8 . 3 x 103
[Ag(NH3)2](a?)+ + 2H 2 0 ( i ) (b) 2.0 x 103 (d) 16.6 x 106
31. A reaction mixture has been made by taken equal concentration of two reactants. It takes 40 minutes for the completion of 50% of the reaction. For the completion of next 50% of the reaction time taken is 80 min. What is the order of the reaction ? (a) 2 (b) 0 (c) 3 (d) 1 32. When m-cblorobcnzaldehyde is treated with 50% KOH solution, the product(s) obtained is(are)
B CHEMISTRY TODAY IFEBRUARY'08
40. Which of the following hormone increases the pulse rate and blood pressure ? (a) Estrogen (b) Adrenaline (c) Cortisone (d) Thyroxine 41. Solubility product of AgCl in water at 18°C is 1.5 x 10~5, then solubility of AgCl at this temperature will be (a) 17.34 x 10^ g/ltr (b) 17.58 x 10 -4 g/ltr (c) 16.34 x 10^ g/ltr (d) 16.58 x IO*4 g/ltr 42. The colour of p-amino azobenzene is (a) orange (b) yellow (c) bismark brown (d) indigo 43. Ka for ascorbic acid (HASC) is 5 x 10~5. Then the value of [H+] in an aqueous solution in which the concentration of ASC" ions is 0.02 (M) will be (a) 5 x 10~7 (b) 5 x IO"9 3 (c) 5 x 10" (d) 1 x IO"9
33. A radioactive isotope has a half life of 2 days. What is the initial amount of the isotope will be left at the end of 8 days ? 1 1 J_ (a) 4 (b) (d) 56 T6 34. 'Azote' is (a) anhy. C a S 0 4 (c) N 2
(b) (d)
Wl-fcG-
.P^T
conc. H N 0 3
o2
35. Two vessels A and B of equal capacity containing gases both at 1 atm are connected together. If the temperature remains constant the pressure of the mixture is (a) 0.5 atm (b) 1 atm (c) 1.5 atm (d) 2 atm 36. An example of a psychedilic agent is (a) DNA (b) LSD (c) DDT (d) TNT 37. The density of a certain mass of a dry gas at 27°C and 760 mm pressure is 2.5 gm/ltr. Its density at 7°C and 740 mm pressure will be (in gm/litre) (a) 0.9 (b) 1 (c) 1.2 (d) 2.3 38. The values of heat of formation of S 0 2 and S 0 3 are -298.2 kJ and -98.2 kJ. The heat of "formation of the reaction S 0 2 + ( l / 2 ) 0 2 - > S 0 3 will be (a) - 2 0 0 kJ (b) -356.2 kJ (c) +200 kJ (d) -396.2 kJ 39. 'PYROPHORIC' is an (a) Alloy of rare earths with Fe, AI, C (b) Alloy of rare earths with S, C, Ca and AI (c) Alloy of transition elements with Fe, AI, C (d) None of these 64
44. What mole of calcium hydroxide is dissolved in aqueous solution having 250 ml to give a solution of pH value 10.65? (Assuming full dissociation) (a) 0.47 x 10"4 (b) 0.48 x 10^ (c) 0.56 x 10^ (d) 0.58 x 10^
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45. Aniline in cold reacts with nitrous acid (NaN0 2 + dil.HCl) to give (a) phenol (b) benzene diazonium chloride (c) nitrobenzene (d) chlorobenzene
••
C2HC
(c) C 2 H 5 - O - C 2 H 5
(d)
C2H2
48. When alkyl halide reacts with dry Ag z O powder, the compound formed is (a) alcohol (b) ether (c) aldehyde (d) ketone
H ...(ii)
H
H
H .(iii)
H - C + Cl 2 —>CH 3 C1 + CI
5.
6.
H CI radical now repeats steps (ii) and (iii) and thus, a chain of reactions is set up. ( a ) : No. of atoms of sodium in 0.0887 mole of Na _ 6.023 x l 0 2 3 x 0.0887 1 = 5.32 x 1022 No. of atoms of oxygen in 0.132 mole of 0 2 = 6.023 x 1023 x 0.132 = 7.97 x 1022 No. of atoms of carbon = 2.65 x 1022 Hence ratios Na : O : C 2 : 3 : 1 Hence empirical formula = Na 2 CQ 3
(a);
SOLUTIONS
H I H- N I H
cr
Co-ordinate bond
7. 1.
....(i)
Cl'+ H - C - H ' f ' H - C ' +HC1
49. A mixture of gases in a gas cylinder at 760 mm pressure contains 65% nitrogen, 15% oxygen and 20% carbon dioxide by volume. The partial pressure of nitrogen is (a) 400 mm (b) 490 mm (c) 494 mm (d) 500 mm 50. Urotropine is obtained when ammonia reacts with (a) HCHO (b) CH3CHO (c) CH3COCH3 (d) C6H5OH
••
H
47. When excess of ethyl alcohol is heated with conc. H 2 S0 4 at 140°C, the product will be (b)
light (U.V)
Free radical
46. Glycerine is a (a) secondary alcohol (b) trihydric alcohol (c) tertiary alcohol (d) ester
(a) C 2 H 4
••
: c i : c i : - J L - 1 — * : c i - + -ci:
(b)
( d ) : Tautomers are as follows: H _ H R - C —N
R- C- N
0
H 2.4,6-trinitroresorcinol
2. (c) S + 0 2
s- S0 2 0.5 gm sulphur when burnt to S0 2 gives - 4.6 kJ
heat 32 gm sulphur when burnt to S0 2 gives - 4.6 x 32 - 294.4 kJ 0.5 Hence, 294.4 kJ is the enthalpy of formation of S0 2 . +
3.
( d ) : HC1 ionizes as HC1 * H + Cl~ and H 2 S0 4 as => H 2 S0 4 — > 2H+ + S0 4 2 . Since, pH of both is same, H + concentration has to be equated Hence, 0.1MHC1 r= 0.05MH 2 S0 4
4.
(c) : Conversion of CH4 to CH3C1 by free radical mechanism is as follows
8. 9.
OH
(b) (c): Deep red coloured chromyl chloride (CrOzCl2) gas is formed. 4NaCl + K 2 Cr 2 0 7 + 3H 2 S0 4 > 2Cr0 2 Cl 2 + 2Na 2 S0 4 + K 2 S0 4 + 3H 2 0 z \
10. ( a ) :
Bicyclo [2.1.0] pentane
11. (d): For a given value of n, I can have values from (n - 1) to zero. Further number of electrons in a subshell = 2(2/ + 1). Total number of electrons in any energy level (n) =
I =
I
n-1
2(21 + 1)
C H E M I S T R Y TODAY I JANUARY '08
12. (a) : HgCl2 + 2NaOH •
->Hg(OH)j + 2NaCl (Unstable)
I
H 2 to triple bond takes place. This reduced product is optically inactive due to the presence of a plane of symmetry in its molecule.
HgO + H20
M e
u
Yellow ppt.
Me
13. (c): KI + H 2 S0 4 — KHS0 4 + HI 2HI + H 2 S0 4 — 2H 2 0 + S0 2 + I 2 r\ CH 3 -*-C=CH : 4 CH,
14. ( b ) :
H
H+
•:o
-CH,
CH,3 — C — CH,i i 2 -H+ CH3H
0 - CH 1 -»• CH, • C - CH ! CH3
15. (d) : From Faraday's first law of electrolysis w = Zit or ZQ (Q - quantity of electricity in C, i = current) Here w = 3.283 g E _ At. wt./Valency Z = 96500" 96500 197/x ~ 96500 it = 4825 C 197x4825 3.283 = xx96500 1 3.283x96500 x 197x4825 x
= 3
20. ( d ) : Melting and boiling points of HBr are greater than those of HCl. 21. ( b ) : C,H 5 NH 2 + CS2 + HgCl 2 C 2 H 5 NCS + HgS + 2HC1 Ethyl isothiocyanate
22. ( b ) : [Fe(CN)6]3_ Fe3+ [Z = 26] = \s2, 2s2p63s2p6d5 3d 4i 4p
?1 t i t !•• 2
CHi 3
c = 0 + NaHS0 3
CR/
•
l-
hybridisation
[Fe(H 2 0) 6 ] 3+ 3d
t
t
t
•
t
t
sp d' h y b r i d i s a t i o n
3s
3p
3d
»®' ®@© o o o o o C h l o r i n e a t o m in g r o u n d state
® ®@© ® o o o o s p ' d h y b r i d i s e d state
OH
CH,
•
!
d sp
16. (c): Acetone with a saturated solution of sodium bisulphite gives crystalline sodium bisulphite addition compound but acetophenone does not. CH
H
CI
\o3-Na+
Acetone sodium bisulphite
17. ( b ) : Step I Step II Step III Step (n-
[3 neutrons, is(energy)] [9 neutrons, 3£"(energy)] = [32«, 31/?] [27 neutrons, 9£(energy)] = [33n, 32E] 1) = [3"" 1 neutrons, 3" ~ 2 E (energy)]
18. (a) : 100 gm of MgS0 4 was initially fed to crystallizer. Out of 100 gm, 80 gm of MgS0 4 is crystallised as MgS0 4 .6H 2 0 Mol. wt. of MgS0 4 = 120 Mol. wt. of MgS0 4 .6H 2 0 = 228 120 gm of MgS0 4 gives 228 gm MgS0 4 .6H 2 0 228x80 80 gm of MgS0 4 gives =
—^—
= 152.00 gm 19. (b) : In the presence of Pd-BaS0 4 ci.v-addition of 66
C H E M I S T R Y TODAY IFEBRUARY'08
24. (a) : S 0 3 on dissolving in 98% H 2 S0 4 gives oleum S0 3 + H,S0 4 - • H 2 S 2 O 7 Oleum
If dil. H 2 S0 4 is used, oleum will be immediately converted in H 2 S0 4 . H2S207 + H 2 0 > 2H 2 S0 4 25. (a) : CC14 (pyrene) has highest chlorine content due to greater number of chlorine atoms. 26. ( d ) :
Ag+
»[Ag(NH3)2I
Cu
[Cu(NH3)4]
Cd2
[Cd(NH,).]2
C o m p l e x ions are f o r m e d
Na+
> No complex formation with ammonia solution
27. ( c ) : Radius of any ion Radius of H atom in ground state Z (of any ion) = ° f A = 0.17A 28. (d) : [2KI + CuS0 4 2CuI 2 4KI + 2CuS0 4
> K 2 S0 4 + Cul 2 ] x 2 » 2CuI + I 2 » 2K 2 S0 4 + 2CuI + I 2
or
'
1
/I
2 =
2
33. ( c ) : According to the question, half life (tU2) = 2 days time (t) = 8 days So, n (no. of half life) t 4 n/2
29. (c) : •.• 14 gm of nitride ion (N ~) has 6.023 x 10 23 N 3 ^ion 4.2 gm of nitride ion (N3~) 23 x 4.2 = 6.023 x l 0 14 Now, V 1 nitride ion (N3 ) has 6 valence electron 6.023 x l 0 2 3 x 4.2 . / x t 3 _, J4 ion(N" )
=
6.023 x 10 23 x 4.2 x 6 p = 1 - 8 NA
30. ( d ) : [Ag(H 2 0) 2 ] + + NH3(Q9) [Ag(NH 3 )(H 2 0 (a9) )] + + H 2 O (0 Kx = 2.0 x 103 C
C
[Ag(NH3)2(^)]+
C
[Ag(NH3)(H20(a9))]
X C
c
c
Since
36. ( b ) : LSD (Lysergic acid diethylamide) is an example of psychedilic agent, a hallucinogen drug which helps in controlling behavioral patterns, regulatory systems including mood, hunger, temperature, etc. (2)
(»') [Ag(H20)2(a?)] NH3 From equation (i), (ii) and (iii) it is evident K ~ K\K2 = 2 x 103 x 8.3 x 103 = 16.6 x 106 31. ( a ) : Initial concentration of both the reactant = a Half life (tU2) = 40 min After 50% completion of reaction = ^ Half life (tV2) = 80 min
OT
'
( f l/ 2 )i _ ( ^ Y " 1 ^1/2)2 l " J '
40 = ( _ a _ " " 1 80 \2a
Pi P? 37. ( d ) : As we know ~~pt~ ~ ~tTt~ r v\ 22 Here, v e are given Pi = 2.5 gm/litre, p 2 = ? 7", = (273 + 27) K = 300 K T2 = (273 + 7)K = 280 K P1 = 760 mm, P2 - 740 mm
(3)
[Ag(NH3)2(ag)]+ xr2
PAVA+PbVB ~ Volume of the mixture lxV + lxV - = 1 atm 2V
(1)
(ii)
L
(2)
35. (b) : Let the volume of each vessel be V litre. The volume of the mixture becomes 2V litre.
NH 3(fl9)
[Ag(H 2 0) 2(a?) ] + + 2NH 3(a?) [Ag(NH 3 ) 2(a?) ] + + 2H 2 O (0
N0)
- (2) 16 34. ( c ) : Antoine Lavoisier proposed the name azote to N 2 gas in 1789 because it did not support respiration and was therefore "lifeless".
C
K
=t =
So, the fraction of isotope left \4
+
[Ag(NH3)tH2Q( ))] 7c [Ag(H20)2]+ ^(ag) [Ag(NH 3 )(H 2 0 (a?) )] + + NH 3(a?) + [Ag(NH 3 ) 2(a4) )] + H20(Q K2 = 8.3 x 103 =
or, n = 2
32. ( c ) : m-Chlorobenzaldehyde has no a-hydrogen and hence gives Cannizzaro's reaction.
3
•'•
n - 1= 1
P2 =
Pi r 2 . P2 '1 '1 2.5 x 280 x 740 760x300 = 2.3 gm/litre.
38. ( c ) : Values of heat formation of S0 2 = -298.2 kJ and that of S 0 3 = -98.2 kJ. Therefore, S w + O2(g) ' •SO 2(g) AHt = -298.2 kJ and ....(i) S w + (3/2)0 2 t e ) - •SO 3(g) AH2 = -98.2 kJ ...(ii) Subtracting equation, (i) from (ii), we get SOz + (l/2)0 2 — ^ S0 3 Hence AH = -98.2 - (-298.2) = 200 kJ. 39. (a) : 'PYROPHORIC' is an alloy of rare earth elements with Fe, Al and C and it is used to prepare ignition devices. B C H E M I S T R Y TODAY IFEBRUARY'08
CHjOH
40. ( b ) : Helps in fight or flight reaction. 41. ( b ) : AgCl is a binary electrolyte. AgCl Ag + + Cl-
Formula
Therefore, .v2 = Ksp or s = Solubility of AgCl = ^(1.5) x 10~10 = 1.225 x 10"5 gm-molecule/litre = 1.225 x 10"5 x 143.5 gm/litre = 17.58 x 10^ gm/litre 42. (b) 43. (b)
As Kh =
1x10' -14
^
5 x 10" J
10
= 2 x IO" Hydrolysis reaction ASC'l[lq) At equilibrium (0.02 - x) =
HASC + OH" x x
0.02
Now, by applying the formula .2 xx x x Ku : ao2 0.02 2 2 X 1
, 0
°=(M => x2 = 2x IO"10 x 0.02 = 2 x IO"10 x 2 x 10"2 => x 2 = 4 x IO"12 =>^2x10^ => [OH"] = 2 x IO"6 1 xlQ- 1 4 rIJ+1 ••• =5> Cr2C>7~ > MnO^ (b) M n 0 4 > Cr 2 07 _ > S 2 0 | " (c) S 2 0 | - > MnC>4 > C ^ O , " (d) Cr 2 0^- > S 2 0 | - > M n 0 4 0
0
22. Compound^U^jJ^ on removal of proton gives a
(a) ^(diamond) + ®2(g)
C02(?)
(b) 1/2 H 2(g) + 1/2 F % ) HF te) (c) N 2(g) + 3H 2(g) 2NH[3(J) 3( (d) CO (g) + 1/2 0 2 ( s ) C( '2(g) 28. The basic character of the transition metal monoxides follows the order (a) VO > CrO > TiO > FeO (b) CrO > VO > FeO > TiO (c) TiO > FeO > VO > CrO (d) TiO > VO > CrO > FeO 29. At CMC, the surface molecules (a) decompose (b) become completely soluble (c) associate (d) dissociate
carbanion. The most stable carbanion should be 0 0 0 0 II II II II (a) / \ / \ (b) / \ / \
30. The activity of a radioactive isotope is 3000 counts per minute at a certain time and 2736 counts per minute 48 hours later. What is its half-life? (a) 831 h (b) 521 h (c) 361 h (d) 1.44 h
0 0 II II (c) / S / \
31. Soap removes grease by (a) adsorption (b) emulsification (c) coagulation (d) none of these
(d) all of these.
23. When a given amount of water is heated from 2°C to 8°C, its volume varies with temperature according to the curve (a)
(b)
T CC)
f(°C)
/A
(c)
vy
(d) T(°C)
T(° C) 15
24. Lattice defect per 10 NaCl is 1. How many lattice defects are observed in 1 gram mole of NaCl? (a) 1014 (b) 6.02 x 1023 8 (c) 6.02 x 10 (d) none of these 25. When one mole of a substance melts reversibly at fusion point, 7} at constant pressure, which of the following relations is correct? AH f AS f (a) A S f = ~ f (b) A H f = Y T
AHf
Tf = ~ASJ 26. Least mobile ion is (a) [Be(H 2 0)„] 2+ (c) [Mg(H 2 0)„] 2+
(d) both (a) and (c) (b) [Na(H 2 0)„] + (d) [Li(H 2 0)„] +
27. Which of the following reactions defines AWfr2NH30;). The rate of this reaction can be expressed in terms of time derivative of concentration of N 2(ff) , H2 or NH 3 Identify the correct relationship amongst the rate expressions. (a)
d[N2]= dt
rate = -
(b) „ t e = (C)
ratc^
dt 4N2]
(d) rate = -
ld[H2]=14NH3] 3 dt 2 dt
=- 3 ^ ™ = dt 1 4 H 2 ]
= dt 3 4N2]_ dt
2
d [ N R i ]
dt
1 4 N H 3 ]
= dt 2 dt 4H2]_4NH3] dt
dt
19. Solution of 0.1 NNH 4 OH and 0.1 NNH 4 C1 has pH 9.25. Then pKh of NH 4 OH is (a) 9.25 (b) 4.75 (c) 3.75 (d) 8.25 20. For the electrochemical cell, M\M+\\X~\ X, E°(M+/AI) = 0.44 V and E°(x/x~) = 0-33 V, From this data, one can deduce that (a) M + X —> Ivt + X~ is the spontaneous reaction (b) M* + X~ —> M + X is the spontaneous reaction (c) ECM = 0.77 V (d) Ece]l = - 0.77 V. . 21. What is the decreasing order of strength of bases? OH", NH 2 -, H - C = C", CH 3 - CH 2 (a) CH 3 - CH 2 - > NH2^ > H - C = C- > OH" (b) H - C =s C" > CH 3 - CH2~ > NH 2 " > OH~ (c) OH" > NH 2 - > H - C = C" > CH 3 - CH 2 (d) NH 2 " > H - C = C" > OH" > CH 3 - CH2". 22. An S N 2 reaction at an asymmetric carbon of a compound always gives (a) an enantiomer of the substrate (b) a product with opposite optical rotation 44
(c) a mixture of diastereomers (d) a single stereoisomer. 23. 3 moles of ethanol react with one mole of phosphorus tribromide to form 3 moles of bromoethane and one mole of X. Which of the following is X? (a)
H3P04
(b)
H3P02
(C)
HP03
(d)
H3P03.
24. Deep blue colour formed by addition of copper(II) sulphate solution to ethylamine is due to formation of (a) free Cu 2+ ions in solution (b)
(NH4)2S04
(d)
CU(OH)2. 1—CO
25.
\
CO-
(C)
NaOH
NH
* I
[CU(C2H5NH2)4]2+
Br,/KOH
•II
In the above sequence, II is (a) P-alanine (b) a-alanine (c) ethylenediamine (d) y-aminobutyric acid.
SECTION - B Direction: In the following questions more than one of the answers given may be correct. Select the correct answers and mark it according to the code. Code: (a) 1, 2 and 3 are correct (b) 1 and 2 are correct (c) 2 and 4 are correct (d) 1 and 3 are correct 26. (1) (2) (3) (4)
Which of the following have the same mass? 0.1 mole of S0 2 gas 6.02 x 1022 molecules of S0 2 gas 1.204 x 10 23 molecules of 0 2 gas 0.1 mole of 0 2 gas.
27. At constant volume, for a fixed number of moles of a gas, the pressure of the gas increases with increase in temperature due to (1) increase in the average molecular speed (2) increased rate of collision amongst molecules (3) increase in molecular attraction (4) decrease in mean free path. 28. Ground state electronic configuration of nitrogen atom can be represented by (i)
¥1
t
I
t
(2)
t
t
t
(3)
t
I
(4)
1
1 C H E M I S T R Y TODAY | JUNE 06
29. (1) (2) (3) (4)
Dipole moment is possessed by 1,4-dichlorobenzene cz's-1,2-dichloroethene /ra«5-l,2-dichloroethene trans-1,2-dichloro-2-pentene.
30. (1) (2) (3)
Which of the following forms ideal solution? ethyl bromide + ethyl iodide ethyl alcohol + water benzene + toluene (4) chloroform + benzene.
31. The enthalpy change for the process C (graphite) —» C (g) is called (1) heat of vaporisation (2) heat of sublimation (3) heat of atomisation. (4) heat of allotropic change 32. (1) (2) (3)
Which of the following statement s) is(are) correct? The conjugate base of H 2 P0 4 ~ is HP0 4 ~. The pH of 1.0 x IO"8 M HCl solution is 8. Auto protolysis constant of water increases with temperature. (4) When a solution of a weak monoprotic acid is titrated against a strong base at half neutralisation point, pH = l/2p Ka. 33. When Cl2 gas is passed through hot NaOH, oxidation number of CI changes from (1) - 1 to 0 (2) 0 to - 1 (3) 0 to +7 (4) 0 to +5. 34. Which of the following statement/s is/are not correct? (1) rust is Fe 2 0 3 (2) saline water slows down rusting (3) pure metals undergo corrosion faster than impure metals. (4) Zn-Cu cell is called Daniell cell 35. For a first order reaction (1) the degree of dissociation is equal to (1 - e~kl) (2) a plot of reciprocal concentration of the reactant versus time gives a straight line (3) the pre-exponential factor in the Arrhenius equation has the dimension of time -1 . (4) the time taken for the completion of 75% of the reaction is thrice the tm of the reaction 36. Decrease in atomic number is observed during (1) a-emission (2) positron emission (3) electron capture (4) P-emission. 45 CHEMISTRY TODAY | JUNE 06
37. Which of the following pairs of elements have almost similar atomic radii? (1) Zr, Hf (2) Mo, W (3) Co, Ni (4) Sn, Pb. 38. .^-Hybridisation is found in the structures of (1) 0 3 (2) NH 3 (3) NOj(4) H 2 0 . 39. Highly pure dilute solution of sodium in liquid ammonia (1) shows blue colour (2) exhibits electrical conductivity (3) produces sodium amide (4) produces hydrogen gas. 40. Sodium sulphate is soluble in water but barium sulphate is sparingly soluble because (1) the hydration energy of Na 2 S0 4 is more than its lattice energy (2) the lattice energy of BaS0 4 is more than its hydration energy (3) the lattice energy has no role to play in solubility (4) the lattice energy of N a 2 S 0 4 is more than its hydration energy. 41. The metals that cannot be obtained by electrolysis of the aqueous solution of their salts are (1) Ag (2) Mg (3) Cu (4) AI. 42. (1) (2) (3) (4)
White phosphorus (P 4 ) has six P - P single bonds four lone pairs of electrons P - P - P angle of 60°. four P - P single bonds
43. The anodic mud obtained during electrorefining of Cu contains (1) Ag (2) Fe (3) Au (4) Zn. 44. Tautomerism is exhibited by (1)
(4)
45. (1) (2) (4)
(0)-CH=CH-OH
0 = Q = 0 An aromatic molecule will have (4n + 2) 7t-electrons be planar (3) be cyclic. have 4n rc-electrons
46. The greater stability of ter/-butyl carbocation over methyl carbocation can be explained on the basis of (1) +I-effect of the methyl group (2) hyperconjugation effect of the methyl groups (3) electromeric effect of the methyl groups (4) -I-effect of the methyl groups. 47. When nitrobenzene is treated with Br z in presence of FeBr 3 , the m a j o r product formed is m-bromonitrobenzene. The statements which are related to obtain the m-isomer are (1) the electron density on meta carbon is more that at ortho and para-positions (2) the intermediate carbonium ion formed after initial attack of Br + at the /we?a-positions is least destabilised (3) loss of aromaticity when Br + attacks at the ortho and para positions and not at /wefa-position (4) easier loss of H + to regain aromaticity from the meta position than from ortho and para positions. 48. /7-Chloroaniline and anilinium hydrochloride can be distinguished by (1) Sandmeyer reaction (2) NaHC0 3 (3) AgN0 3 (4) carbylamine test. 49. Hydroxylamine reacts with (1) CH 3 COCl (2) CH 3 COCH 3 (3) CH 3 COOC 2 H 5 (4) CH 3 CONH 2 . 50. Under Wolff-Kishner reduction conditions, the conversions which may be brought about are (1) benzophenone into diphenylmethane (2) benzaldehyde into benzyl alcohol (3) cyclohexanone into cyclohexane (4) cyclohexanone into cyclohexanol.
(c): N 2 : KK a(2sf a*(2sf n(2Px)2 n(2Py)2 c(2pzf Bond order = 3 N 2+ : KK o(2.?)2 cr*(2.v)2 n(2px)2 n(2P>)2 a(2pz)] Bond order = 2. We know that higher the bond order, higher is the bond dissociation energy as well as greater is the stability. Dissociation energy of N 2 > dissociation energy of N 2 + . 5.
6.
7.
8.
(c) : tm = 24 hrs = 1 day X=^ = 0.693 day' 1 hn 2.303 . N0 2.303, 100 t=log—= log I N 0.693 12,5 2.303 log8 = 3 days. 0.693 (b) : Zn : Is2 2s2 2p6 3s2 3p" 4s2 3d10 Fe2+ : Is2 2s2 2ph 3s2 3p6 3d6 Ni 3+ : l.v2 2.S'2 2p" 3s2 3p6 3d1 Cu + : Is2 2s2 2p6 3s2 3p6 3dw (a) : If r is the radius of first orbit, then radius of orbit of the H-atom is rn2.
9. (c) : Magnetic moment = jn(n + 2) B.M Magnetic moment of Ti ion = 1.73 BM V«(« + 2) =1.73 or, n(n + 2) = 3 or, n = 1. /. Ti ion has 1 unpaired electron i.e. 3d] configuration. Complete configuration of Ti3+ ion is Ti3+ (Z = 22) : [Ar]18 3a". 10. (d) : AgCl + 2NH 3 11. (c) : (i =
SOLUTIONS 1.
(a) : KA for H 2 0 2 = 1.55 x 10"12.
2.
(a) : Mol. mass of H 2 0 2 = 2 x 1 + 16 x 2 = 34 2 Percentage of hydrogen = — xlOO 100
17 3.
+2
(b) : Mn2
= 5.88%.
+4
-*• Mn0 2 + 2e~
molecular mass _ M Eq. mass change in oxidation number 2 4. (a) : Water has a non-linear while C 0 2 has a linear shape. 46
Hi or'
3 RT
I3RT,
^I MI
M M2 3 RT2
[Ag(NH 3 ) 2 ]Cl. P L = 3RT\_ / 3R7i p2 V M\ / V M2 TXM2 MXT2
50x32 800x2
= 1.
12. (b) : Molecular mass of NH 3 = 17 Molecular mass of HCl = 36.5 Rate of diffusion, r oc
1
molecular mass NH 3 will diffuse faster than HCl. So NH 3 vapour will travel a longer distance than HCl vapour in same time. Ring formed will be nearer to HCl bottle. 13. (b): For gases to show ideal behaviour there should be no attractive or repulsive forces among the molecules.
CHEMISTRY TODAY | JUNE 06
14. (b) : A7} = K,x m = 1.86 x 0.5 = 0.93°C A Tf= T°f - Tf Tj = r f - A7>= 0 - 0.93 = - 0.93°C.
CHXONH,
25.
CHjCOOH
15. (d)
(I)
16. (c): When k increases, rate of reaction also increases. PZ k = - E/RT For k to increase, P, Z, Tshould increase and E should decrease. 17. (a) : Rate = *[N 2 0 5 ] = 6 . 2 x l O ^ x 1.25 = 7.75 x 10-4 mol L-1 s"1. 18. (a) : N 2 0 f ) + 3 H 2 a f ) - » 2 N H 3 { l f ) 4N2] I d[u2] Instantaneous rate = _ dt 3 dt 19. (b) : As pOH = pKh + log
l 4NH3] dt
[salt]
i
[base] but [NH4C1] = [NH4OH], pOH = pKh :. pKh = pOH = 14 - pH = 14 - 9.25 = 4.75 20. (b) : M | M+ \\X~\X The two half cell reactions for the cell are M M+ + e~ or, X + e~ X~ M+X^> M+ + X£°oeii = E°X/X—E°M+/M = 0.33 V - 0.44 V = - 0.11 V. As E°ceii is negative the reaction involved is nonspontaneous. The reverse reaction, however, will be spontaneous. M + + X~ M +X 21. (a) : The strength of their conjugate acids are in the order: H 2 0 > HC = CH > NH 3 > CH 3 - CH 3 Stronger the acid weaker is its conjugate base. Therefore correct order of strength of their conjugate bases is CH 3 CH,~ > NH,- > HC = C" > OH22. (d): In S N 2 reaction, an optically active alkyl halide gives an optically active product. The product may not have opposite optical rotation to that of the alkyl halide as the two are not enantiomers. Therefore a single stereoisomer is the product. 23. ( d ) : 3CH 3 CH,OH + PBr3
3CH 3 CH 2 Br + H 3 P0 3
24. (c) : Cu 2+ + 4C 2 H 5 NH 2
[Cu(C 2 H 5 NH 2 ) 4 ] 2+
W tetraethylamine copper(ll) ion (deep blue complex)
47 C H E M I S T R Y TODAY | JUNE 06
Br 2 /KOH ^
P
a
CH2NHj
CH 2 COOH p-alanine (II)
26. (a) : 0.1 mol of S0 2 = 6.4 g 6.02 x 10 22 molecules of S 0 2 = 0.1 mol S 0 2 = 6.4 g 1.024 x 1023 molecules of 0 2 = 0.2 mol 0 2 = 6.4 g 0.1 mole of 0 2 = 3.2 g. 27. ( b ) : With increase in temperature, average speed of the molecules as well as rate of collision increases. 28. (c) : In (2) and (4), the unpaired electrons have spin in the same direction. CI 29. (c) : [ O J Y CI H - C - CI II CI - C - H
(H-0),
H - C - CI II H - C - CI
(H#0)
(U = 0)
CI CI I I C H 3 - C = C - C H , - C H 3 i.e.,
CH,-C-C1 II C1-C-CH,CH3 (trans)
(M. * 0) 30. (d) : (1) and (3) have pairs of similar liquids. Hence they form ideal solution. 31. (c) : C (() —> C ( j f ) . This process is sublimation as well as conversion of crystalline allotropic form (graphite) to amorphous form (gas carbon). 32. (d) -1 +5 33. (c) : 3C12 + 6NaOH—> 5NaCl + NaCIO, + 3H,0 . 34. (a) : Rust is Fe 2 0 3 -JcH 2 0. Saline water speeds up rusting. Pure materials almost do not corrode. 35. (d) : Degree of dissociation = 1 - e~k' k = Ae-W' As EJRT is dimensionless, therefore A has the dimension of k. 36. (a) : Electron capture is addition of atomic number decreases by one.
. Hence
37. (a) : Due to lanthanide contraction, the atomic radii of Zr and Hf and Mo and W are almost similar. In case of Co and Ni, the contractive effect of increased nuclear charge is almost balanced by the increase in size due to increasing shielding effect. As a result, the atomic radii of Co and Ni are nearly the same. 38. (c) : NH 3 and H 2 0 contain jp 3 -hybridized N and O atoms respectively. 39. (b) : Dilute solution of Na in liquid NH 3 will not produce sodium amide and hydrogen gas instantaneously. These are metastable and when catalysed give hydrogen and amide.
than that at o- and /^-positions; and the intermediate carbonium ion resulting from meta attack of Br+ is least destabilised. Thus (1) and (2) are correct. 48. (a) : Sandmeyer reaction on p-chloroaniline gives p-dichlorobenzene which is a solid (m.p. 325 K) while that on anilinium chloride gives chlorobenzene which is a liquid (b.p. 405 K). CI
42. (a): White phosphorus (P4) has tetrahedral structure in which each P atom lies at the corners of the regular tetrahedron. There are six single P - P bonds, four lone pairs of electrons and P - P - P bond angle of 60° in the P4 structure. 43. (d) : Noble metals like Ag and Au settle down as anode mud. 44. (a) : (1) shows tautomerism since aldehydes are more stable than vinyl alcohols. C 6 H 5 - CH = CH - OH •«— ? C6HS - CH 2 - CH = O (2) shows tautomerism because enol form is stabilized by aromatic character.
rvo
X //
OH
o
OH (3) shows tautomerism because enol form is stabilized by H-bonding.
q ^
ch
reaction m.p. 325 K. Sandmeyer^
NH,C1~
40. (b): The solubility increases as the hydration energy increases and the lattice energy decreases. 41. (c) : Mg and AI are highly electropositive metals and cannot be obtained by electrolysis of their aqueous salt solutions.
Sandmeyer
NH,
Zn2*(aq) +2Ag(s).
19. (d) : 2A + B P P
13. ( b ) : The actual pH of the sample can change with temperature due to a change in the hydrogen ion activity in the solution, because ionization of compounds and hydrogen ion activity in the solution may be temperature dependent. For pure water, pH decreases with increasing temperature. But the degree of influence of temperature on pH is a function of the alkalinity of the water. [The molecules are moving faster, with more energy, so we may be sensing more of the ions in a time .frame].
20. (d) : Tertiary alcohol, 2-methylpropan-2-ol CH, I
14. (b) : Depression in freezing point, ATR — KF XM = 1.86 x 0.05 = 0.093. Freezing point of the solution = Freezing point of solvent -AT) = 0°C - 0.093°C = - 0.093°C. 15. (d) : At STP volume « number of moles weight and number of moles mol. weight weight .'. volumecc 2-; mol. weight If volume remains constant then weight molecular weight. One litre Cl2 weight more at STP. 16. (b) : In Haber process, N, + 3H 2 ^ 2 N H 3 Four moles of reactants from two moles of NH,. Volume of NH, relative to the total volume of reactants is half. 17. (b) : CO(g) + ^ 0 2 ( g ) —> C0 2 (g) At constant volume A// =-67.71 kcal. Heat of reaction (at constant pressure) AH = - 6 7 . 7 1 + ^ - i j x 2 x i 0 " 3 x290 = -67.71 -0.290 =-68.0 kcal. CH, I 18. (b) : CH — CI-I — C H - CH, + HC1—> I OH 3-methyl-2-butanol CH, ' I CH - C H - C H - CH,+ H 2 0 CI 2-chloro-3-methyl butane 50
(PA)
CH — C
-C + D _
0.7x1.2 = 4.2 atm" (0.5)2 xO.S
P'„H
CH,^ w j ] | r e a c t fastest with HBr because its
OH - O H group will be replaced easily due to the +/ effect of three - C H 3 groups. 21. ( a ) : CH 3 CHO reduces Fehling solution to give a precipitate of Cu 2 0 while C s H 5 CHO does not have any reaction with Fehling solution. 22. ( d ) : Gem-dihalides are those having two halogen atoms on the same carbon atom. 23. (b) : Allene is C H , = C = C H , Therefore, three C-atoms are joined by 3a- and 3nbonds. 24. ( d ) : Aldehydes which have atleast one H-atom at a-carbon atom show aldol condensation. CI I 25. (c) : C H , - C H - C - C O O H is the strongest acid i
CI due to the - / effect of the two chlorine atoms on the alpha carbon. Therefore, it will be most highly ionised in water. 26. (b) : Amide R - C - N H , ' II O c-bonds and a rc-bonds 27. (b) : R—CH= O + H,NR' (-11,0)
R-CH=N-R' Schiffs base (anils)
28. (a) : Compound (a) have no a-H-atom, which is necessary condition to show Cannizzaro's reaction. 29. (b) : Benzyl alcohol though aromatic does not burn with sooty flame (exceptional nature). CH, 30. ( a ) : r
V
CHC1Anhy.AICI,
+HCI
(Friedal-Craft reaction) Anhydrous A1C13 acts as a halogen carrier. Mechanism : (i)
CH3C1+ A1CI, H> CH,® + A1C14"
(ii) [ O J +e CH,—>
?H, C H E M I S T R Y TODAY | JUNE 06
j density is a physical quantity derived f r o m two fundamental quantities mass and length.
A\ (iii) I •,©; l N CH,+ AICi;
C H
' \
RedP
C H
' \
Propane +H,0 + 21, 32. (c): Three isomers ortho, meta and para are formed. 33. ( b ) : When propyne is treated with aqueous H 2 S 0 4 in presence of H g S 0 4 it adds one molecule of water. CH,C— CH + H -, 0
H,SOJ
~ ,,„>
HgSO,
OH CH,-C=CH, (Unstable)
O tautome satio
"
42. (b) : The balanced equation for the formation of water is 2H 2 f e ) + O 2 0 ; ) ^ 2 H 2 O (/) In this reaction, 1 volume of hydrogen combines with 0.5 volume of oxygen to form 1 volume of water and 0.5 volume of oxygen remains unused. That is why. oxygen is an excess reagent. 43. (d) : According to Charles' law that at constant pressure, the volume of a given mass of a gas is directly proportional to its absolute temperature i.e.. T. And the Charles law is applicable only to gases. Gas constant {K) for 1 mole of a gas is termed as universal gas constant (R). • And for one mole (i.e.. n = 1) K = nR = 1 * R= R.
" > CH,— C— CH, (Acetone)
44. (a) : The viscosity is the resistance offered by a liquid to its flow. Dissolving some amount of sg.lt in 34. (d) a liquid increases its viscosity i.e., resistance to flow 35. (c) : Oxides of both phosphorus as well as sulphur • increases. are acidic in nature but ' P ' is a solid while ' S ' is a gas. i 4,5. (c) : In the Balmer series of hydrogen spectrum, Oxides of Na is a strong base. the highest wavelength or lowest energy is between n\ 36. ( a ) : Barium salts are quite stable because of great = 2 and n 2 = 3 (where n = Principal quantum number). electropositive nature of Ba. Hence barium compounds 46. (b) : Heat of neutralisation is the change in heat possess high decomposition temperature. i content of a system when one gram equivalent of an 37. (a) : Ozone oxidises moist sulphur to sulphuric acid is neutralized by one gram equivalent of a base acid. and vice versa. The heats of n e u t r a l i s a t i o n of S+ H , 0 + 3 0 3 -> H 2 S 0 4 + 3 0 2 t . 38. (b) : Hydrolysis of cupric ions produces H' ions according to the reaction Cu 2+ + 2 H , 0 Cu(0H) 2 + 2H + i.e., it acts as Lewis acid. Therefore turns blue litmus paper red (characteristics property of acids). 39. (c) : Hydrolysis of CIO;, 2C10 2 + H j O —> HCIO, + HC10, produces both HCIO, and HCIO,. Thus it is a mixed anhydride of both HC10 2 and HCI0 3 . 40. (b) : Chromyl-chloride test: Cr0 2 Cl 2 + 4NaOH Na 2 Cr0 4 + 2NaCl + 2H z O yellow
(CH 3 COO) 2 Pb + N a 2 C r 0 4 PbCr0 4 -i + 2 C H 3 C 0 0 N a . yellow
41. (a) : A physical quantity, which is obtained with the help of two or more fundamental quantities, is a derived quantity. Since densityJ C H E M I S T R Y TODAY | MAY '06
=
AIIMS EXPLORER
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77-;—-— . Thus the Volume
51
HNO, + NH 4 OH and NH 4 OH + CH 3 COOH are - 5 1 . 6 6 kJ and -55.78 kJ respectively. 47. (b) : From the Le Chatelier's principle Hb (s) + 0?ul (Haemoglobin) (Oxygen)
^
Hb0 2 ( s ) (Oxyhaemoglobin)
Thus in the lungs, partial pressure of oxygen (O) appreciably shows forward reaction. However, when the oxygen passes through the tissues, its partial pressure decreases to favour the backward reaction and releasing oxygen. Also from the Le Chatelier's principle that CO, (f!) + H , 0 , / , ^ H + („(/) + HC0 3 - („v) Thus in tissues, carbon dioxide (C0 2 ) dissolves in H : 0 due to high pressure, whereas in lungs C 0 2 is released due to low pressure. 48. (b) : The species which are present in a solution but do not take part in the reaction and are also omitted while writing the net ionic reactions, are called spectator ions e.g., Zn + 2H4" + 2C1" Zn 2+ + 2CL + H 2 . In this reaction, Cl~ ions could be omitted and are called spectator ions because these appears on both side of the reaction.Terpentine, phosphorus and metals like zinc and lead can absorb oxygen from air in the presence of water. The water is oxidised to hydrogen peroxide. The phenomenon of formation of H 2 0 2 by the oxidation of H 2 0 is known as auto-oxidation e.g., the chemical reaction PbO, + H 2 0 PbO + H 2 0 2 . 49. ( d ) : The electron afinities of iodine (I), bromine (Br), chlorine (CI) and fluorine (F) are - 2 9 5 , - 3 2 4 , - 3 4 8 and - 3 3 3 kJ moL' respectively. Thus the order of electron affinities of halogens is CI > F > Br > I. Fluorine has no vacant J-orbitals, therefore no excitation of valence electrons is possible. Thus it does not exhibit variable oxidation states. 50. ( c ) : 2 K M n 0 4 + H 2 S 0 4 -> K 2 S0 4 + Mn 2 0 7 + H , 0 In this reaction, explosion takes place due to the formation of manganese oxide (Mn 2 0 7 ), which is explosive. 51. ( c ) : In silicon dioxide (Si0 2 ), the atom of silicon (Si) is tetrahedrally bonded to four oxygen atoms(O), and each oxygen atom is bonded to two silicon (Si) atoms. Thus the structure of S i 0 2 extends in three dimensions to form a network solid. The molecule of carbon dioxide (C0 2 ) is linear with net zero dipole moment. That is why, Si0 2 is solid but C 0 2 is gas. 52. (d) : Si(CI) 4
CC14 + H20 ( C a r b o n tetrachloride) (Water)
(Silicicchloride)
52
+ H,0
(Water)
Si(OH) 4
(Silicic hydroxide)
no action and +
4HC1 '
(Hydrochloric acid)
Thus CCI4 is resistant to hydrolysis while SiCl 4 is easily hydrolysed. Electronic configuration of silicon (Si) is Is 2 ,2s 2 ,2p", 3s 2 ,3p 2 . Thus it does not contain d-orbital in its atom. 53. (a) : All alkali metals dissolve in liquid ammonia to give deep blue ammonical solution. The dissolution of the metal is accompanied by its ionisation. Blue colour of the solution is due to the formation of ammonical electrons. 54. ( c ) : The electronic configuration of Fe-,+ ions in [ F e t C N y 3 - is \s2 2s2 2p" 3s2 3pb 3 a n d electronic configuration of Fe 2+ ions in [Fe(CN) 6 ] 4 " is Is 2 2s2 2p" 3s2 3pb 3d 6 . Since [Fe(CN)6]3~ has unpaired electrons, that is why, it is weakly paramagnetic. And in [Fe(CN)6]4~ there are no unpaired electrons, that is why, it is diamagnetic. 55. ( a ) : The boiling points of alcohols are much higher as compared to the boiling points of their corresponding hydrocarbons due to the intermolecular hydrogen bonding in alcohols. 56. (b) : Certain organic substances change directly from solid to vapour, without passing through the liquid state and vice-versa. This is called sublimation. The substances, having vapour pressure equal to the atmospheric pressure but much below their respective melting points, can be sublimated and purified by this method. Distillation is the process of heating a liquid to convert it into the vapour, and then condensing the vapour to get back the liquid. 57. (d): In geometrical isomerism, two atoms or groups attached to each doubly-bonded carbon atom, should be different. If one of the two doubly-bonded carbon atoms carries two identical atoms or groups, then the molecule does not exhibit geometrical isomerism. 58. ( a ) : Ethers are insoluble in water, as their molecules are neither capable of forming H-bonds with water (H 2 0) molecules nor capable of breaking H-bonds between water molecules. 59. (d): Fumes and smoke are particulate pollutants. And hydrocarbon and ozone are gaseous air pollutants. 60. ( b ) : Enzymes are proteins, which act as catalysts in biochemical reactions. Since pH affects activity of enzymes as p r o t o n a t i o n - d e p r o t o n a t i o n causing denaturation of the protein structures, therefore the activity of enzyme is pH dependent. The change in pH value of an enzyme affects the solubility of the enzyme in water.
• CHEMISTRY TODAY | JUNE 06
Practice Paper for
on
21s* May
UP-CPMT 2006
2006
By: Er. Arvind Tripathi (6. Tech, IT-BHU) Momentum, Gorakhpur 1. Ionic radii of the halogens is found to be greater than their corresponding atomic radii because addition of extra electrons cause (a) an increase in the number of protons (b) an increase in the number of neutrons (c) a greater repulsive force among the electrons (d) none of these. 2. (a) (b) (c) •(d)
Which of the following statement is correct? H 2 0 and OF, both are linear in shape H 2 0 is linear whereas OF2 is bent molecule both H 2 0 and OF 2 have a bent structure H , 0 is bent whereas OF, has a linear structure.
3. Arrange the following compounds in order of increasing dipole moment. 1. toluene II. /n-dichlorobenzene III. o-dichlorobenzene IV. p-dichlorobenzene. (a) I < IV < II < III (b) IV < I < II < III (c) IV < I < III < II (d) IV < II < I < III. 4. (a) (b) (c) (d)
The volume of a gas depends on the temperature only depends on pressure only depends on the number of moles of the gas only depends on the temperature, pressure and the number of moles of the gas.
5. If 40.00 ml of 1.60 M HCl and 60.00 ml of 2.00 M NaOH are mixed, then the molar concentration of OH~ in the resulting solution will be (a) 0.056 M (b) 0.28 M (c) 0.56 M (d) 0.053 M. 6. For a solution in which both the components are volatile, Raoult's law states that (a) the relative lowering of vapour pressure is equal to the mole fraction of the solute (b) the relative lowering of vapour pressure is proportional to the amount of solute in solution (c) the vapour pressure of the solution is equal to the mole fractions of the solvent 53 CHEMISTRY TODAY | JUNE 06
(d) the saturated vapour pressure of each component in the mixture is equal to the product of the mole fraction of that component and the saturated vapour pressure of the component when it is pure. 7. The vapour pressure of a dilute aqueous solution of cane sugar (C l 2 H 2 2 O n ) at 373 K is 740 mm Hg. Calculate the mole fraction of cane sugar, (a) 0.974 (b) 0.36 (c) 0.029 (d) 0.026 8.
The addition of more nitrogen on the equilibrium •.•NJW+3HIW ^ 2NHJW in a vessel at constant volume is that it (a) shifts the equilibrium to the right (b) shifts the equilibrium to the left (c) increases the rate of formation of ammonia by 10 times (d) does not affect the equilibrium. 9. Which of the following salt will hydrolyze in water to form basic solutions? I. KCI II. CuS0 4 III. K,P0 4 (a) I, II and III (b) I and II only (c) I only (d) III only. 10. For the reaction, A + B -> C, the following results were obtained for kinetic runs at the same temperature. initial rate |0|o Ml. mol L"1 mol L _l molLr's- 1 0.20 0.40 0.40 What is the overall (a) 0 (b) 1 11. (a) (b) (c) (d)
0.10 0.20 0.10 0.80 0.20 0.80 order of the reaction? (c) 2 (d) 3.
For an elementary process the order and molecularity are identical the order is twice of molecularity the order is three times the molecularity there is no relation between the order and molecularity.
12. Given £°A|3+/AI = -1.66 V, E°Cu2+/Cu = +0.34 V. What will happen if we store aluminium nitrate in coper tumbler? (a) the tumbler gets coated with aluminium (b) the solution becomes blue (c) an alloy of copper and aluminium is formed (d). there is no reaction. 13. The length of the side of the unit cell for lithium is 352 pm, calculate its atomic radius. Lithium forms body-centred cubic crystal. (a) 304 pm (b) 76 pm (c) 608 pm (d) 152 pm. 14. If the radii of A+ and B~ are 95 pm and 181 pm respetively, then the coordination number of A+ will be (a) 12 (b) 8 (c) 6 (d) 4. 15. (a) (b) (c)
The nuclear fission reaction involves the combination of two nuclei to form single nuclide splitting of single nuclide into two nuclei combination of alpha and beta particles
22. In P 4 O 10 , each phosphorus atom is linked with .. oxygen atoms. (a) 2 (b) 3 (c) 4 (d) 5. 23. The correct IUPAC name of the compound O
CH 3
II
I
is
CH 3 - CH - C - CH, - CH CH,
CH,
CH,
(a) (b) (c) (d)
2,5-dimethylheptan-4-one 3,6-dimethylheptan-4-one 2-ethyl-5-methylhexan-3-one 1 ,l-dimethyl-4-ethylpentan-3-one.
24. Which of the following Newman projection formula for 1,2-dichloroethane represents the staggered form?
(d) combination of [H and ^H . 16. If 360 grams of glucose (C 6 H, 2 0 6 ) is dissolved in 2000 grams of water (essentially 2 litres), what will be the freezing point of this solution? (a) - 6.58°C (b) - 3 . 7 2 ° C (c) - 1 . 8 6 ° C (d) - 0.51°C. 17. (a) (b) (c) (d)
Sodium metal is obtained by the electrolysis of concentrated aqueous NaCl heating N a 2 0 with H 2 heating fused sodium chloride electrolysis of fused sodium chloride.
18. Which of the following tetrahalide of lead is not known? (a) Pbl 4 (b) PbBr 4 (c) PbCl 4 (d) PbF 4 . 19. In the reaction : NaOH + S -> X + H 2 0 + Na 2 S, X is (a) N a , S 0 3 (b) Na 2 S0 4 (c) N a , S , 0 , (d) Na 2 S 2 . 20. The oxidation state of iron in its brown ring complex (test for nitrate ion) [ F e ( H 2 0 ) 5 N 0 ] S 0 4 is (a) +1 (b) +2 (c) +3 (d) 0. 21. A m o n g the f o l l o w i n g , the lowest degree of paramagnetism per mole of the compound at 298 K will be shown by (a) M n S 0 4 - 4 H 2 0 (b) F e S 0 4 - 6 H , 0 (c) C u S 0 4 - 5 H 2 0 (d) N i S 0 4 - 6 H , 0 . 54
25. The product X in the following reaction is CH 3 CH
(a)
CHCH,
CH,CH-CH-CH, OH
H,0,
-»- X,
HIO4
> X
(b) CH, - COOH
OH
(c) CH,CHO
(d)
OH O I II CH,CH - C - CH,
26. The compound X in the following reaction is HC
CH
(OO,
X (a) glyoxal only (b) mixture of glyoxal and formic acid (c) butanone (d) ethanal only. 27. Chloretone is (a) CCljNO,
(ii) H T
(b) (CH 3 ),C(OH)CCl 3
C H E M I S T R Y TODAY | JUNE 06
(c) CH 3 C0CH 2 CHC1 2
(d) (CH3)2C =
CC12
34. 0.0012 mol of CrCl 3 -6H 2 0 was passed through a cation exchange resin and acid coming out of it required 28.5 mL of 0.125 M NaOH. Hence complex is (a) [Cr(H 2 0) 5 Cl]Cl 2 • H 2 0 (b) [Cr(H 2 0) 4 Cl 2 ] • 2 H 2 0 (c) [Cr(H 2 0) 6 ]Cl 3 (d) [Cr(H 2 0) 3 Cl 3 ] • 3H 2 0.
28. The compound X in the following reaction CHj - CH = (a) (b) (c) (d)
CH - CHO
H,/Ni
» X is
CH 3 CH 2 CH 2 CHO CH 3 CH — CH - CH 2 OH CH 3 CH 2 CH 2 C'H 2 OH CH, - CH — CH - CH 3 .
29. A—j-'l
,,
—> a-hydroxy propionic acid.
(//) dilute H 2 S 0 4
The structure of A is (a) CH 3 COOH (b) CH2 = CH - COOH (c) CH3CHO (d) CH3COCH3. 30. Identify the compound B in the following reaction. NaN0 2 /H 2 S0 4 0°C
(a)
( Q y so3H
(b)
(c)
< O ^ 0 H
(d)
steam distilled
-+A H O
3
S - © - N H
2
31. When 10 ml of ethyl alcohol (density 0.7893 g/ml) is mixed with 20 ml of water (density 0.9971 g/ml) at 25°C, the final solution has a density of 0.9571 g/ml. The percentage change in total volume on mixing is (a) 3.1% (b) 2.4% (c) 1% (d) none of these. 32. Which is incorrect statements? (a) a solute will dissolve in water if hydration energy is greater than lattice energy (b) if the anion is large compared to the cation, the lattice energy will remain almost constant (c) solubility of 1IA hydroxide is in order Be(OH) 2 < Mg(OH) 2 < Ca(OH) 2 < Sr(OH), (d) all are correct. 33. Which of the following pairs of isomers and types of isomerism are correctly matched? 1. [Co(NH 3 ) 5 (N0 2 )]Cl 2 and [Co(NH 3 ) 5 (ONO)]Cl 2 .... linkage 2. [Cu(NH 3 ) 4 ][PtCU] and [Pt(NH,) 4 ][CuCl 4 ] .... coordination 3. [Pt(NH 3 ) 4 CI,]Br 2 and [Pt(NH 3 ) 4 Br 2 ]Cl 2 .... ionisation Select the correct answer using the codes given below: (a) 2 and 3 (b) 1 , 2 and 3 (c) 1 and 3 (d) none of these.
55 C H E M I S T R Y T O D A Y | JUNE 06
35. Which of the following statement about Millikan's oil drop experiment is true? (a) when the electrifc field is turned on, all the oil drops move towards the positively charged plate (b) the charge on each oil drop is the electronic charge (c) in the absence of the electric field, the speed with which the drop falls depends only upon the acceleration due to gravity (d) some oil drops become positively charged and some become negatively charged after colliding with gaseous ion. 36. Total vapour pressure of mixture 1 mol A (P°4 = 150 torr) and 2 mol B ( = 240 torr) is 200 mm. In this case (a) there is positive deviation from Raoult's law (b) there is negative deviation from Raoult's law (c) there is no deviation from Raoult's law (d) molecular masses of A and B are also required. Jcl(AG) TAS and AG = AH + 7 dT then variation of EMF of a cell E, with temperature T is given by AH -AS AG AS (c) — (d) (a) (b) nF ~~nF nF nF 37. If AG = AH-
38. Silver salt of a dibasic acid has 54% silver. Hence molecular weight of the organic compound is (a) 200 (b) 400 (c) 93 (d) 186. 39. ZnS does not crystallise in the NaCl structure. It is due to (a) the r+/r~ ratio is 0.402, too low to avoid anionanion contact in the NaCl structure (b) the r + / r ratio is 0.402, too high to avoid cationcation contact in the NaCl structure (c) both are correct (d) none is correct. 40.
CH,CH = CH, J
CO, H „ [CoH(CO),l
—
- 125° pressure
H, Cu-Zn
product This represents oxo method of alcohol synthesis. Product can be
(a) CH 3 CH,CH 2 CH 2 OH
(b)
CH 3 -CHCH 2 OH CH,
(c) both are true
(d) none is true.
41. End product of the following sequence of reactions is CH
=
CH3MgBr>
CH
CO^H^O*
HgSOj/HiSOj >
>
o
(a)
I! CH3-C-COOH
(c)
O II CH j - C - C H O "
(b) CHj(COOH) 2 o (d)
H-C-CH2COOH
45. When KI (excess) is added to I. CuS0 4 II. HgCI, III. Pb(N0 3 ) 2 (a) a white ppt. of Cul in I, an orange ppt. of Hgl 2 in II and a yellow ppt. of Pbl, in III (b) a white ppt. of Cul in I, an orange ppt. dissolving to Hgl42~ in II, and a yellow ppt. of Pbl, in III (c) a white ppt. of Cul, Hgl, and Pbl 2 in each case (d) none is correct. 46. A B (oxide) + CO,, B + H 2 0 -> C, C + C 0 2 -> A (milky), C + NH4C1 — ^ D (gas) D + H 2 0 + C0 2 E ; E + NaCl F F - A * Na 2 C0 3 + C 0 2 + H , 0 Name of the process is (a) Solvay (b) ammonia-soda (c) both are correct
42.
47. CO, gas along with solid (K) is obtained when sodium salt (X) is heated. (AO is again obtained when CO, gas is passed into aqueous solution of (Y). X and Y are (a) Na 2 C0 3 , N a 2 0 (b) Na,C0 3 , NaOH (c) NaHCOj, N a , C 0 3 (d) Na,C0 3 , NaHCO,.
(ii) H , 0 +
A and B are
(a)
HO-^-TMO,(CH3)2NH
(b)
H0-^O)-OH'(CH3)2NH
(c)
HO - < 0 > - N O , CH,CH 2 NH 2
(d) none of these. 43
'
(3)~
M g B r + CH
(a)
(Q)-CH2OH
(c)
( 0 / ~ R*71" C H 2
2 -CH2 —
(b)
C 0 2 + FeO I. 1800 °C B. CO C + CO, II. 800°C C. FeO + CO Fe + C 0 2 111. 500-600°C D. CaO + Si0 2 CaSi0 3 IV. 400°C Choose the correct alternate. (a) A-1V, B-11I, C-II, D-I (b) A-IV, B-II, C-III, D-I (c) A-l, B-ll, C-1V, D-II1 (d) A-I, B-II, C-III, D-IV. 56
(d) none is correct.
CH,CH,CHCH, 3 3 V ci 11 CH,
CH3CHCH2CI CHJ
CH3-C-C] CH3
III IV Increasing tendency for SN1 and S N 2 reaction is A. SN1 : I < III < II < IV B. S n 2 : IV < II < III < I (a) A and B both are correct C H E M I S T R Y TODAY | JUNE 06
(b) only A is correct (d) both incorrect.
MTG-MCQ's Memory Contest
(c) only B is correct
50. An organic compound of molecular formula C 4 H 6 (A), forms precipitates with ammoniacal silver nitrate and ammoniacal cuprous chloride. A has an isomer B one mole of which reacts with one mol of Br2 to form l,4-dibromo-2-butene. A and B are (a) CH, - CH 2 - C = CH and CH, = CH - CH = CH 2 (b) CH 3 - C = C - CH 3 and CH 3 - CH = C = CH, H2CV
(O H2C (d) C H 3
(d)
C = C H 2 and "
- c == c -
a I. The exams: National Chemistry 1L Olympiad / International Chemistry '>\ Olympiads/OrissaJEE/AIIMS/AFMC/ \ EAMCET / DCE/ Karnataka CET/ UP SEE / Bihar CECE/Jharkhand CECE/Haryana CET/ Punjab PMT & PET / NDA /UGC - JRF/JIPMER/ Maharashtra CET/Raj. PMT & PET / MP PMT & PET/AMU. . . . 2. The requirements: Plenty of grey cells, photographic memory, neat handwriting, eagerness to do something different and of course, taking exams. 3. The task: Take the exam, come home and write down as many questions (with
(
CH2 — CH ' CH, CH
CH3
/C1K CH2^ | >H2 ^ C H ^ ANSWERS
1. 6. 11. 16. 21. 26. 31. 36. 41. 46.
(c) (d) (a) (c) (c) (b) (a) (b) (b) (c)
2. 7. 12. 17. 22. 27. 32. 37. 42. 47.
3. 813. 18. 23. 28. 33. 38. 43. 48.
(c) (d) (d) (d) (c) (b) (d) (c) (a) (c)
(b) (a) (d) (a) (a) (c) (b) (d) (b) (d)
4. 9. 14. 19. 24. 29. 34. 39. 44. 49.
(d) (d) (C) (c) (d) (c) (c) (a) (a) (a)
5. 10. 15. 20. 25. 30. 35. 40. 45. 50.
(c) (c) (b) (a) (c) (c) (d) (c) (b) (a)
all choices and their answers) you can
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57 CHEMISTRY TODAY | JUNE 06
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SOLVED PAPER
CBSE-PMT (Prelims) - 2006 1. by (a) (b) (c) (d)
The orientation of an atomic orbital is governed principal quantum number azimuthal quantum number spin quantum number magnetic quantum number.
2. The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is (a) 1 (b) 2 (c) 3 (d) 4. 3. Which of the following is not a correct statement? (a) multiple bonds are always shorter than corresponding single bonds (b) the electron-deficient molecules can act as Lewis acids (c) the canonical structures have no real existence (d) every ABS molecule does in fact have square pyramid structure. 4. Which of the following species has a linear shape? (a) 0 3 (b) N0 2 " (C) S0 2 (d) N0 2 + . 5. Which of the following is not isostructural with SiCl 4 ? (a) NH 4 + (b) SC14 (c) S0 4 2 " (d) P0 4 3 ". 6. Which of the following is the most basic oxide? (a) SeO, (b) Al 2 0 3 (C) Sb 2 0 3 (d) Bi 2 0 3 . 7. The correct order regarding the electronegativity of hybrid orbitals of carbon is (a) sp < sp2 < sp3 (b) sp > sp2 < sp3 2 3 (c) sp > sp > sp (d) sp < sp2 > sp3. 8. The correct order of the mobility of the alkali metal ions in aqueous solution is (a) Rb + > K + > Na + > Li + (b) Li+ > Na + > K + > Rb + (c) Na + > K + > Rb + > Li+ (d) K + > Rb + > Na + > Li+. 9. The electronegativity difference between N and F is greater than that between N and H yet the dipole 58
moment of NH 3 (1.5 D) is larger than that of NF 3 (0.2 D). This is because (a) in NH 3 the atomic dipole and bond dipole are in the opposite directions whereas in NF 3 these are in the same direction (b) in NH 3 as well as in NF 3 the atomic dipole and bond dipole are in the same direction (c) in NH 3 the atomic dipole and bond dipole are in the same direction whereas in NF 3 these are in opposite directions (d) in NH 3 as well as in NF 3 the atomic dipole and bond dipole are in opposite directions. 10. Which one of the following orders is not in accordance with the property stated against it? (a) F2 > Cl2 > Br2 > I2 : bond dissociation energy (b) F2 > Cl2 > Br2 > I2 : oxidising power (c) HI > HBr > HC1 > HF : acidic property in water (d) F2 > Cl2 > Br2 > I2 : electronegativity. 11. In which of the following molecules are all the bonds not equal? (a) NF 3 (b) C1F3 (c) BF3 (d) A1F3. CI 12. The IUPAC name of (a) (b) (c) (d)
0 2,3-dimethylpentanoyl chloride 3,4-dimethylpentanoyl chloride 1-chloro-l-oxo-2,3-dimethylpentane 2-ethyl-3-methylbutanoyl chloride.
13. The human body does not produce (a) enzymes (b) DNA (c) vitamins (d) hormones. 14. During the process of digestion, the proteins present in food materials are hydrolysed to amino acids. The two enzymes involved in the process proteins
e zyme( 4)
"
' >
polypeptides enzyme (B)
>
amino acids,
are respectively C H E M I S T R Y TODAY | JUNE 06
(a) invertase and zymase (b) amylase and maltase (c) diastase and lipase (d) pepsin and trypsin. 15. the (a) (c)
The general molecular formula, which represents homologous series of alkanols is C„H2„ + 2 0 (b) C„H 2 „0 2 C„H 2 „0 (d) C „ H 2 n + I 0 .
16. The appearance of colour in solid alkali metal halides is generally due to (a) interstitial positions (b) F-centres (c) Schottky defect (d) Frenkel defect. 17. CsBr crystallises in a body centred cubic lattice. The unit cell length is 436.6 pm. Given that the atomic mass of Cs = 133 and that of Br = 80 amu and Avogadro number being 6.02 x 1023 mol -1 , the density of CsBr is (a) 4.25 g/cm 3 (b) 42.5 g/cm 3 3 (c) 0.425 g/cm (d) 8.25 g/cm 3 . 18. Given : The mass of electron is 9.11 x 10-31 kg, Planck constant is 6.626 x 10"34 Js, the uncertainty involved in the measurement of velocity within a distance of 0.1 A is (a) 5.79 x 105 ms-' (b) 5.79 x 106 ms"1 7 1 (c) 5.79 x io ms" (d) 5.79 x 108 ms"1. 19. A plot of log(x/m) versus log p for the adsorption of a gas on a solid gives a straight line with slope equal to (a) log/: (b) -logK (c) n (d) 1 In. 20. A solution containing 10 g per dm 3 of urea (molecular mass = 60 g mol"1) is isotonic with a 5% solution of a nonvolatile solute is (a) 200 g mol-1 (b) 250 g mol"1 (c) 300 g mol-' (d) 350 g mol- 1 . 21. 1.00 g of a non-electrolyte solute (molar mass 250 g mol-') was dissolved in 51.2 g of benzene. If the freezing point depression constant, Kf of benzene is 5.12 K kg m o r 1 , the freezing point of benzene will be lowered by (a) 0.2 K (b) 0.4 K (c) 0.3 K (d) 0.5 K. 22. Identify the correct statement for change of Gibbs energy for a system (AGsystem) at constant temperature and pressure. (a) If AGsystem < 0, the process is not spontaneous.
59 C H E M I S T R Y TODAY | JUNE 06
(b) If AGsystem > 0, the process is spontaneous. (c) If AGsystem = 0, the system has attained equilibrium. (d) If AGsystem = 0, the system is still moving in a particular direction. 23. Assume each reaction is carried out in an open container. For which reaction will AH = AE? (a) 2CO (g) + 0 2 —> 2C0 2 (b) H 2 f e ) + B r 2 f e ) - > 2 H B r ( K ) (c) C w + 2H 2 0 - » 2H 2 + C02 (d) P C I S W - * P C 1 3 W + C1 2 W . 24. For the reaction: CH4 + 20 2 (g)
C02
+ 2H20
m,
AH r = - 1 7 0 . 8 kJ mol" 1 . Which of the following statements is not true? (a) The reaction is exothermic. (b) At equilibrium, the concentrations of C 0 2 ^ and H 2 0 (/) are not equal. (c) The equilibrium constant for the reaction is given
[co2] [CH4][02]" (d) Addition of CH4 t e ) or 0 2 cause a shift to the right. by
at equilibrium will
25. For the reaction, 2A + B 3C + D, which of the following does not express the reaction rate? (a) (c)
d[A] 2 dt d[B] dt
(b) (d)
d[C] - 3 dt d[D] dt
26. Consider the reaction: N 2 (jr) + 3H2 (x) —> 2NH, The equality relationship between d[ H 2 ] dt 4NH3J _ 4 H 2 ] 4NH3] (a) (b) dt dt dt 4 N H 3 ] _ 2C/[H 2 ] (c) + dt 3 dt 4NH3]_ 3J[H2] (d) + dt 2 dt
4NH3] 7— dt
and
1 4H2] 3
dt
2 7 . £° F e 2 + /Fe = - 0 . 4 4 1 V a n d £° F e 3 + / F e 2 + = 0 . 7 7 1 V, t h e
standard EMF of the reaction Fe + 2Fe 3+ -> 3Fe 2+ will be (a) 0.111 V (b) 0.330 V (c) 1.653 V (d) 1.212 V.
28. A hypothetical electrochemical cell is shown below. ©
A | A+ (.xM) || B+ (yM) | B The emf measured is + 0.20 V. The cell reaction is (a) A + B+ A+ + B (b) A+ + B A + B+ + + (c) A + e~ A; B + e~ B (d) the cell reaction cannot be predicted. 29. (a) (b) (c) (d)
A solution of acetone in ethanol obeys Raoult's law shows a negative deviation from Raoult's law shows a positive deviation from Raoult's law behaves like a near ideal solution.
30. During osmosis, flow of water through a semipermeable membrane is (a) from solution having lower concentration only (b) from solution having higher concentration only (c) from both sides of semipermeable membrane with equal flow rates (d) from both sides of semipermeable membrane with unequal flow rates. 31. Which of the following pairs constitutes a buffer? (a) HC1 and KC1 (b) HNO, and NaNO z (c) NaOH and NaCl (d) HN0 3 and NH 4 N0 3 . 32. The hydrogen ion concentration of a 10"8 M HC1 aqueous solution at 298 K (KW = 10~14) is (a) 1.0 x 10"8 M (b) 1.0 x 10"6 M 7 (c) 1.0525 x lO" M (d) 9.525 x 10"8 M. 33. The enthalpy and entropy change for the reaction: Br 2(J) + C l 2 t e ) - » 2 B r C I w are 30 kJ mol"1 and 105 J K 1 mol"1 respectively. The temperature at which the reaction will be in equilibrium is (a) 300 K (b) 285.7 K (c) 273 K (d) 450 K. 34. A1 2 0 3 can be converted to anhydrous A1C13 by heating (a) A1,0 3 with Cl 2 gas (b) A1 2 0 3 with HC1 gas (c) A1 2 0 3 with NaCl in solid state (d) a mixture of A1 2 0 3 and carbon in dry Cl2 gas. 35. In which of the following pairs are both the ions coloured in aqueous solution? (a) Ni 2+ , Cu + (b) Ni 2+ , Ti3+ 3 3+ (c) S c \ Ti (d) Sc3+, Co 2+ . (At. no. : Sc = 21, Ti = 22, Ni = 28, Cu = 29, Co = 27) 36. Copper sulphate dissolves in excess of KCN to give 60
(a) Cu(CN) 2 (c)
(b) CuCN
[CU(CN)4]3-
(d)
[CU(CN)4]2~
37. More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is (a) more active nature of the actinoids (b) more energy difference between 5/and 6d orbitals than that between 4 / and 5d orbitals (c) lesser energy difference between 5/and 6d orbitals than that between 4/and 5d orbitals (d) greater metallic character of the lanthanoids than that of the corresponding actinoids. 38. [Cr(H 2 0) 6 ]Cl 3 (at. no. or Cr = 24) has a magnetic moment of 3.83 B.M. The correct distribution of 3d electrons in the Chromium of the complex is (a) 3dxy}, 3dyz\
3dj
(b) 3 d u 2 _ y 2 ) \ 3 d / , (c)
3dj
3dxy\
(d) 3 d x y \ 3dyz\
3dx;
[ C O ( N H 3 ) 4 ( N 0 2 ) 2 ] C 1 exhibits (a) linkage isomerism, geometrical isomerism and optical isomerism (b) linkage isomerism, ionization isomerism and optical isomerism (c) linkage isomerism, ionization isomerism and geometrical isomerism (d) ionization isomerism, geometrical isomerism and optical isomerism. 39.
40. In a set of reactions propionic acid yielded a compound D. CH3CH2COOH
SOC1,
^
B-
NH,
^
c
KOH Br,
> D
The structure of D would be (a) CH 3 CH,NH 2 (b) CH 3 CH,CH,NH, (c) CH 3 CH,CONH, (d) CH 3 CH,NHCH 3 . 41. (a) (b) (d)
Which of the following is not chiral? 2-hydroxypropanoic acid 2-butanol (c) 2,3-dibromopentane 3-bromopentane.
42. Ethylene oxide when treated with Grignard reagent yields (a) primary alcohol (b) secondary alcohol (c) tertiary alcohol (d) cyclopropyl alcohol. C H E M I S T R Y TODAYJANUARY'06
43. Which of the following is more basic than aniline? (a) benzylamine (b) diphenylamine (c) triphenylamine (d) p-nitroaniline. 44. The enthalpy of hydrogenation of cyclohexene is -119.5 kJ mol"1. If resonance energy of benzene is -150.4 kJ mol"1, its enthalpy of hydrogenation would be (a) - 358.5 kJ mol"1 (b) - 508.9 kJ mol"1 (c) - 208.1 kJ mol-' (d) - 269.9 kJ mol"1. 45. Nucleophilic addition reaction will be most favoured in (a) CH,CHO O
Magnetic quantum number describes the orientation or distribution of electron cloud. Spin quantum number represents the direction of electron spin around its own axis. 2. (b): Molecular orbital configuration of a diatomic molecule of an element with atomic number 16 is KK(c2.j)2 (cr*2.s)2 (02p x ) 2 (n2p})2 (nip,)1 (n*2p,,)' (n*2p.)1 Number of unpaired electrons = 2. 3. (d) : For AB5 molecules, there are three possible geometries i.e. planar pentagonal, square pyramidal and trigonal bipyramidal.
(b) CH, - CH2 - CH2C - CH, (c) (CH 3 ) 2 C = O (d) CH 3 CH 2 CHO. 46. The major organic product in the reaction, CH 3 - O - CH(CH 3 ) 2 + HI products is (a) CH 3 I + (CH 3 ) 2 CHOH (b) CH 3 OH + (CH 3 ) 2 CHI (c) ICH 2 OCH(CH 3 ) 2 (d) CH3OC(CH3), I 47. Self condensation of two moles of ethyl acetate in presence of sodium ethoxide yields (a) ethyl propionate (b) ethyl butyrate (c) acetoacetic ester (d) methyl acetoacetate. 48. A carbonyl compound reacts with hydrogen cyanide to form cyanohydrin which on hydrolysis forms a racemic mixture of a-hydroxy acid. The carbonyl compound is (a) formaldehyde (b) acetaldehyde (c) acetone (d) diethyl ketone. 49. >AvfNH(CH2)NHCO(CH2)4COt^ is a (a) homopolymer (b) copolymer (c) addition polymer (d) thermosetting polymer. 50. Which one of the following is a peptide hormone? (a) adrenaline (b) glucagon (c) testosterone (d) thyroxin. SOLUTIONS 1. (d): Principal quantum number represents the name, size and energy of the shell to which the electron belongs. Azimuthal quantum number describes the spatial distribution of electron cloud and angular momentum. 61 C H E M I S T R Y TODAY |DECEMBER'0547
planar pentagonal
square pyramidal
trigonal bipyramidal
Out of these three geometries, it is only trigonal pyramidal shape in which bond pair-bond pair repulsions are minimum and hence this geometry is the most probable geometry of AB5 molecule. sp2 hybridisation of N-atom and the presence of one lone pair on it, N0 2 " has angular shape. 4.
03 :
( d ) : N 0 2 " : Due to
^ - X * O
116.8°
N o
115° O
V-shaped o
S 0 2 : Due to the presence of one lone pair of electros in one of the three sp 2 -hybrid orbitals and sp2 o 119.5° 0 + hybridisation of S or S atom, S 0 2 molecule has angular (V-shaped) structure. N 0 2 + : Due to sp hybridisation of N+, N 0 2 + ion has linear shape. :0=Nr=0: 5. (b) : SiCl4, NH 4 + , S0 4 2 " and P0 4 3 " ions are the examples of molecules/ions which are of ABT type and have tetrahedral structure. SC14 is ,-lB4(lone pair) types species. Although the arrangement of five sp3d hybrid orbitals in space is trigonal bipyramidal, due to the presence of one lone pair of electron in the basal hybrid orbital, the shape of AB4 (lone pair) species gets distorted and becomes distorted tetrahedral or see-saw.
6.
(d) : Se0 2 —> acidic oxide A1 2 0 3 —> amphoteric Sb 2 0 3 —> amphoteric Bi 2 0 3 —» basic oxide.
4
8. (a) : The alkali metal ions exist as hydrated ions M + (H 2 0)J. in the aqueous solution. The degree of hydration, however, decreases with the ionic size as we move from Li+ to Cs+. In other words, Li+ ion is most highly hydrated. e.g. [Li(H20)6]+. Since the mobility of ion is inversely proportional to the size of their hydrated ions, therefore, amongst the alkali metal ions, lithium has the lowest ionic mobility. Rb + (aq) > K + (aq) > Na + (aq) > Li + (aq) 9. (c) : The dipole moment of NF 3 is 0.24 D and of NH 3 is 1.48 D. The difference is due to fact that while the dipole moment due to N - F bonds in NF 3 are in opposite direction to the direction of the dipole moment of the lone pair on N atom which partly cancel out, the dipole moment of N - H bonds in NH 3 are in the same direction of the dipole moment of the lone pair on N atom which adds up as shown below.
x; H
NF, (moments subtract)
o 2,3-dimethylpentanoyl chloride 13. (c) : Certain organic substances required for regulating some of the body processes and preventing certain diseases are called vitamins, which cannot be synthesised by the organism. pepsin
14. (d) : Proteins
proteases*
polypeptides
trypsin cliemotrypsin*
aC
'ds
15. (a) : All alcohols follow the general formula C„H2„ + 2 0 . CH 3 OH [CH 2 + 2 0 ] ; C 2 H 5 OH [C 2 H (2 x 2) + 2 0 ] n = 1, n — 2 16. (b): F-centres are the sites where anions are missing and instead electrons are present. They are responsible for colours. 17. (a) : Density of CsBr
ZxM
1x213 in i — r r - = 4.25 g/cm J (436.6 x 10 ) x 6.023 x 10 18. (b) : Ax-mAv = h/4n
-34 a i m-io A 1 1 . 3 1 \ 6.626x10 0.1x10 x9.11x10 x Av — 4x3.143 6.626x10 -34 Av 0.1 xlO - 1 0 x9.1 lx 10~31 x 4x3.143 = 5.79 x 106 ms- 1 .
NH3 (moments add)
11. (b) : The basal CI - F (CI - FA) bond length is equal to 1.60 A while each of the two axial CI - F (CI - Fa) bond lengths is equal to 1.70 A .
31111110
H
10. (a) : X-X bond F - F CI - CI Br - Br I - I Bond dissociation 38 57 45.5 35.6 energy (Kcal/mol) The lower value of bond dissociation energy of fluorine is due to the high inter-electronic repulsions between non-bonding electrons in the 2p-orbitals of fluorine. As a result F - F bond is weaker in comparison to CI - CI and Br - Br bonds.
50
.CI
12. (a) :
7. (c): Electronegativity of carbon atom is not fixed. It varies with the state of hybridisation. Electronegativity of carbon increases as the j-character of the hybrid orbital increases. C (sp) > C (sp2) > C (sp1)
t;
[2
L7
° "
1.60 A, CI • 1.70 A | F
slope = — n 19. (d)
log log K (intercept)
O
log P-
-X
This is according to Freundlich adsorption isotherm. 20. (c) : For isotonic solution, osmotic pressure of urea = osmotic pressure of nonvolatile solute 10 _ 5 6tbdO(W = wxToO => - = 300 g m o l - ' . 1000x/C xw ,„ = — / — 21. (b): m ——— W x A7"
c A = -1000x5.12x1 or, n250 51,2x A r
-10 CHEMISTRY TODAY|FEBRUARY
1000x5.12x1 — — = 0.4 K. 51.2x250 22. (c) : The criteria for spontaneity of a process in terms of AG is as follows: (a) If AG is negative, the process is spontaneous. (b) If AG is positive, the process does not occur in the forward direction. It may occur in the backward diection. (c) If AG is zero, the system is in equilibrium. The process does not occur. •
AT=
23. (b) : AH = AE + AnRT For H.2 Or) + Br2 2HBr Or) AH = AE. An = 2 - (1 + 1) = 0. 24. (c) : CH 44 Or) + 20y2 : fe) ± C 0 2 to + 2H 2 0 PCH4
HN0 2 and NaNO, are examples of acidic 8
8
+
32. (c) : IO" M HCl = IO" M H . +
7
Also from water, [H ] = IO" . Total [H+] = IO"7 + 0.10 x IO"7 = 1.1 x IO' 7 . 33. (b) : Br 2 (/) + Cl2 2BrCl (s) AH = 30 kJ mol- 1 , AS = 105 JK"1 mol-' AS = —
i.e. 105 = —xlOOO
3 0 x l M = 285.7 K. 105 34. (d): A1203 + 3C + 3CI2 r =
1000 C
°
> 2A1C13 + 3CO vapours cool
• Po2
25. (b) : 2A + B
3C + D
solid anhydrous aluminium chloride
_ ~d[A\ _ d[B]_d[C]_d[D] 2 dt dt 3dt dt Negative sign shows the decrease in concentration. ratc
26. (c) : N 2
+ 3H 2
- » 2NH 3
w
-4N,]_ 4H2]_4NH3] Rate = 2 dt dt 3dt 4 N H 3 ] _ 2 d[H2] Hence dt 3 dt 27. (d) : Fe2+ + 2 2Fe2+ ; E° = 0.771 V —Fe2+ ± 2e~ - Fe ; E° = -0.441 V 2Fe 3+ + Fe 2Fe 2+ ; E° = 1.212 V 28. (a) : From the given expression: At anode : A —» A+ + e At cathode : B* + e -» B Overall reaction is : A + B+ —> A+ + B. 29. (c) : Both the components escape easily showing higher vapour pressure than the expected value. 30. (d) : Osmosis is the phenomenon of flow of pure solvent from the solvent to the solution or from a less concentrated solution to a more concentrated solution through a semipermeable membrane. Common semipermeable membranes are permeable to certain solute particles also. Infact, there is no perfect semipermeable membrane. Therefore we can say that flow of water through a semipermeable membrane takes
50
31. (b) buffer.
Pco7
K
n=-
place both sides with unequal rates.
35. (b) : Sc [Ar] 3d 4s2, Sc3+ [Ar] 2 Ti -> [Ar] 3d 4s2, Ti3+ [Ar] 3d Ni [Ar] 3d 4s2, Ni 2+ [Ar] 3d Cu [Ar] 3d'0 4s 1 , Cu + [Ar] 3 d w 2 2+ Co [Ar] 3d 4s , Co -> [Ar] 3d1 3+ Ti , Ni 2+ and Co 2+ are coloured due to presence of unpaired electrons. 36. (c) : First cupric cyanide is formed which decomposes to give cuprous cyanide and cyanogen gas. Cuprous cyanide dissolves in excess of potassium cyanide to form a complex, potassium cyanide [K3CU(CN)4]. [CUS0 4 + 2KCN CU(CN)2 + K 2 S0 4 ] x 2 2Cu(CN) 2 CU2(CN)2 + (CN), CU2(CN)2 + 6KCN - » 2K3CU(CN)4 2CUS0 4 + 10KCN 2K3CU(CN)4 + 2K 2 S0 4 + (CN), 37. (c) : The 5/"-orbitals extend into space beyond the 6s and 6p-orbitals and participate in bonding. This is in direct contrast to the lanthanides where the 4/-orbitals are buried deep inside in the atom, totally shielded by outer orbitals and thus unable to take part in bonding. 38. (d) : Magnetic moment =
+ 2) 2
3.83 = + or, (3.83) = n(n + 2) or, 14.6689 = n2 + 2n On solving the equation, n = 3. Cr3+ -> [Ar] 3d
d„. d
d2
-10 CHEMISTRY TODAY|FEBRUARY'061
39. (c) : Ionization isomerism arises when the coordination compounds give different ions in solution. [CO(NH3)4(N02)]C1
^
[ C o ( N H 3 ) 4 ( N 0 2 ) 2 } + + CL~
Linkage isomerism occurs in complex compounds which contain ambidentate ligands like N0 2 ", SCN~, CN", 2
S 2 0 3 ' and
CO.
[CO(NH3)4(N02)2]C1 and
[CO(NH3)4(ONO)2]C1
are linkage isomers as N0 2 " is linked through N or through O. Octahedral complexes of the type Ma 4 6 2 exhibit, geometrical isomerism. NH3 NH,
= 3AH - resonance energy = 3 x (-119.5) - (-150.4) = -358.5 + 150.4 = -208.1 kJ moL 1 . 45. ( a ) : The reactivity of the carbonyl group towards the addition reactions depends upon the magnitude of the positive charge on the carbonyl carbon atom. Hence aryl substituent that increases the positive charge on the carbonyl carbon must increase its reactivity towards addition reactions. The introduction of negative group (-1 effect) increases the reactivity while introduction of alkyl group (+1 effect) decreases the reactivity. CH, CH, H \ c=o C—O > ;c=o > / / CH, H H +I-effect and steric hindrance increases
NH,
cis-
trans-
40. (a) : CH3CH2COOH NH 3
SOCI,
->• CH3CH2C0C1 KOH > CH3CH2CONH2•> CH3CH2NH2 Br,
Br 41. (d) : H 3 C - CH 2 - CH - CH, - CH, Due to absence of asymmetric carbon atom. O• / \ 42. (a) : H 2 C—CH 2 + CH3MgBr CH3CH2CH2OMgBr
H
CH 3 OCH(CH 3 ) 2 + HI —> CH3I + (CH 3 ) 2 CHOH 47. (c): Ethyl acetate undergoes Claisen condensation in presence of sodium ethoxide involving a-hydrogen atom in which two molecules of ethyl acetate combine together to form acetoacetic ester. CH 3 COOC,H 5 + CH 3 COOC,H 5
C:H
'°Na »
CH 3 COCH,COOC,H 5 + C,H 5 OH acetoacetic ester
*• CH3CH2CH2OH primary alcohol
43. (a) : Any group which when present on benzene ring has electron withdrawing ( - N0 2 , - CN, - SO,H, - COOH, - CI, - C6H5 etc.) decreases basicity of aniline, e.g. aniline is more basic than nitroaniline and diphenyl amine. While a group which has electron repelling effect ( - NH 2 , - OR, - R etc.) increases basicity of aniline. Thus, benzylamine is more basic than aniline. 44. (c) :
46. (a) : With cold HI, a mixture of alkyl iodide and alcohol are formed. In the case of mixed ethers, the halogen atom attaches to a smaller and less complex alkyl group.
+ H, AH = -119.5 kJ moL + 3H,
48. (b) : CH3CHO + HCN
II I -»- CH,-C—OH I CN II 11,0
CH 3 -C—OH I COOH lactic acid v 49. ( b ) : ^NH(CH,)NHCO(CH,) 4 COiw is formed by the condensation of adipic acid and hexamethylene diamine. It is a copolymer (a polymer made from more than one type of monomer molecules is referred to as copolymer). 50. (b) : Glucagon is a single chain peptide of 29 amino acids, synthesised by the A cells in the Islets of Langerhans of the pancreas.
Enthalpy of hydrogenation of benzene 65 CHEMISTRY TODAY |DECEMBER'05
47
U.
(For Q.lWo. 1 to 60) Only one option is correct and there will be negative marking in these PASSAGE 1 : Read the following passage and answer the questions numbered 1 to 5. When aluminium salts are added to water, Al3+ ions are immediately attracted to the negative end of polar water molecules. They form hexaaquaaluminium (III) ions, [AI(H 2 0) 6 ] 3+ . This is often written simply as Al3+ (aq). However the electric field associated with small, highly charged Al 3+ ion is so intense that it draws electrons in the O - H bonds of water towards itself. This enables the water molecules to become donors. In aqueous solution, free water molecules act as bases and the following equilibrium is established. [A1(H 2 0) 6 ] 3+ + H 2 0 [A1(0H)(H 2 0) 5 ] 2+ + H 3 O + 3+ Thus, solutions of Al salts are acidic, in fact as acidic as vinegar. When a base stronger than H 2 0, e.g. S2~ is added to aqueous aluminium salts further H + ions are removed from [A1(H 2 0) 6 ] 3+ and insoluble aluminium hydroxide precipitates. 2[A1(H 2 0) 6 ] 3+ + 3S2~ (at) 2[A1(0H) 3 (H 2 0) 3 ] w + 3H2S More stronger base can remove 4H+ ions as follows: [A1(H20)6]3+ + 40H- — [AI(OH) 4 (H 2 O)]- w + 4H 2 O (0 1. Which of [A1(H20)6]3+, H,S or H , 0 is the strongest acid? (a) [A1(H 2 0) 6 ] 3+ (b) H 2 S (c) H 2 0 (d) all are same. 2. A base which will behave just like S2~ (a) C0 3 2 (b) CH 3 OH (c) NH 4 (d) N H 2 3. Another ion that would behave similar to Al3+ (HI) in forming an acidic solution is (a) Kf (aq) (b) Ba2+ (aq) 2+ (c) Be (aq) (d) Tl+ (aq). 4. [A1(0H) 3 (H 2 0) 3 ] (.v) more simply written as Al(OH)3 (S) is
(a) acidic (c) neutral
questions.
(b) basic (d) amphoteric.
5. Which gas would get absorbed when passed into a solution of Al3+ (aq)? (b) NO (a) N H 3 (d) 0 2 . (c) CO PASSAGE 2 : Read the following passage and answer the questions numbered 1 to 5. Structural isomers have different covalent linkage of atoms. Stereoisomers are compounds that have same sequence of covalent bonds but differ in the relative dispositions of their atoms in space. Geometrical and optical isomers are the two important types of configurational isomers. The compound with double bonds or ring structure have restricted rotation, so exist in two geometrical forms. The double bonds in larger rings (ring size 10 carbon or large) can also cause geometrical isomerism. The optical isomers rotate the plane of plane-polarised light. A sp3-hybridised carbon atom bearing four different types of substituents is called an asymmetric centre or chirai centre. A chirai object or molecule cannot be superimposed on its mirror image. Stereoisomers that are mirror images of each other are called enantiomers. The stereoisomers that are not mirror images of each other are called diastereomers. Diastereomers have different physical properties. A racemic mixture is optically inactive and contains equal amounts of both the enantiomers. Resolution refers to method of separating a racemic mixture into two pure enantiomers. A meso compound is an optically inactive stereoisomer, which is achiral due to the presence of an internal plane of symmetry or centre of symmetry within the molecule. 6.
The pair showing identical species is
Contributed by Deptt. of Chemistry, Resonance, Kota (Rajasthan) -10 C H E M I S T R Y TODAY | FEBRUARY'0606
and
(a)
-""V'"'//
Ci
photochemical bromination and then treatment with alcoholic KOH followed by reaction with HBr/R,0, give same major product.
H
r CI •OH -Br
(b)
•Et -OH
DH"
and
OH
Br
7.
O
D (+) sucrose
Br and CH,
II3CCI
(R')-l-plienylcthylamine
OH
H
(a) 7 (c) 9
(b) 8 (d) 10.
10. The following two compounds are
(R + S)-2-cliloropropanoic acid
-> (R'R) hydro'ySS (R') + (R)
separation by recrystallisation
(3)
" (R'S)
hydrolysis
> (RO + (S)
Which statement is not correct about the above observation. (a) the product mixture of step-1 is optically active (b) the products R'R and R'S have identical structural formula (c) R'R is nonsuperimposable on R'S (d) R'R and R'S have same solubility in water. 8. Which statement is correct about the following pair of compounds?
(a) (b) (c) (d)
HO
HOH
Observe the following reaction. CH, HOOC .CH, 3 "l H \ / — ( R ' R ) + (R'S) NH, CI H
u7
OH H H
HOOC H
OH
OH
HO
and
(c)
fCI
H A COOH OH
COOH
' V
(d)
CH,OH
Me
Et
HOOC
9. The number of chiral centres present in the following compound is
Br
Me
(I) (II) both give same product with Br,/CCl 4 solution I and II cannot be separated by fractional distillation I and II have different linkage of atoms I and II after catalytic hydrogenation, followed by
-10 CHEMISTRY TODAY | FEBRUARY '06
I (a) identical (c) geometrical isomers
II (b) conformational isomers (d) structural isomers.
11. CoCI42" („v) is blue in colour while [Co(H20)c,]2+ (U(/) is pink. The colour of reaction mixture Co(H 2 0) 6 2+ (at/) + 4Cl- (a9) — CoCl 4 2 - (uq) + 6 H , 0 (/) is blue at room temperature while it is pink when cooled hence (a) reaction is exothermic (b) reaction is endothermic (c) equilibrium will shift in forward direction on adding water to reaction mixture (d) equilibrium will not shift on adding water to equilibrium mixture. 12. Which one of the following best explains why the lattice enthalpy of magnesium chloride is much larger than that of lithium chloride? (a) magnesium has greater electronegativity than lithium (b) magnesium ions have greater polarising power than lithium ions 7
(c) magnesium ions have greater radius than lithium ions (d) magnesium ions have greater charge than lithium ions. 13. The percentage of copper in a copper (II) salt can be determined by using a thiosulphate titration. 0.305 g of a copper (II) salt was dissolved in water and added to an excess of potassium iodide solution liberating iodine according to the following equation. 2Cu 2 %„ ;) + 41- (aq) — 2CuI (s) + I2(a Ph - =
NH2
(b) H
o
54. The reagents of following reaction sequence are respectively
H Q - 0 - C ^ >
2
(5)'
\
(d)
(C)
CH3CQC1/A1C13 ^ (2)
Zn-Hg/HCl/A ^
co
^N^COOH
NH, CI
PliCOCI/Pyridine > (1)
(b)
X
51. The major product of the following reaction sequence will be
3
(3)
(2)
COOH
O
QH
C,H,CR
(4)
I O
C H
C 2 H S CT
H3O+, A
CI
V N - C - / /
(d) 0 , N - < /
(a)
CN
O Me
(T\_ \=/~
52. The dehydration of ethyl alcohol with sulphuric acid at 140°C produces diethyl ether, but ethylene is produced at higher temperature. Assume that ethylene is produced from the ether. Which statement is incorrect regarding mechanism of this reaction? (a) it will be a (3-elimination reaction (b) ethyl alcohol is the leaving group (c) the protonated ether undergoes 1,2-eIimination reaction (d) the energy of activation of ether formation (SN reaction) is higher than energy of activation of alkene formation (elimination reaction).
O Me
(b)
CH3-CH.
V
50. The major monochlorination product of the following compound is Me
(a)
(d)
(b) Na/Iiq. NH 3 ; (c) Li/NH 3 ; \
Q
; TsCl ; KCN ; LiAlH 4 /
(d) KNH, ; CH, =
; TsCl ; NaCN ; H,/Pd C =
O ; TsCl ; KCN ; H,/Ni.
CHEMISTRY TODAY | FEBRUARY '06 12
55. Which of the following is/are the proper sequence of reagents for the conversion? Ph ,OH
O:
>
(a) (b)
PBr 3
PCI 3 ^
Ph-C-H
^
H,S04
>
PhMgBr^
Br 2 ^
alc,
~AA
(c)
KOH
„H ,n0 >
PhCQ 3 H
HO.
(d)
PhMgBr ^ H3OT
MeON/\
(a)
T O 'J
H2S04
X
A
cold alkaline ^ K M n 0 4 solution
(a)
M e O H , H® v
MeO
OH O
C.
P ^ / rF F
" OMe
p
OH
OH
III
IV
(b) I > IV > II > III (d) III > II > IV > I.
58. Compounds A'and T(C 4 H 8 0 3 ) on heating produce W and S (C 4 H 6 0 2 ) respectively. Only S decolourise bromine solution. Both A'and 1'turn blue litmus solution to red and both give white turbidity with Lucas reagent. W is -sweet smelling liquid. X and )' are OH O 0 OH
OH
OH
Mg/ether
>z-
Na2Cr207, H2S04
(d)
CH3 Br
57. Arrange the alcohols in order of reactivity towards gaseous HBr.
(a)
P
IVHjO"1
/
\I OH
'
60. Which laboratory test can not be given by the end product of reaction sequence?
O
0//XH
O
-OH
(C)
(d)
OH OH I II (a) II > III > IV > I (c) I > II > III > IV
;
3,4-dimethyl-3-hexanol OH OH (b)
OMe
F
»
59. The structure of the starting material X is
0 s 0 4 alkaline
H2SQ4 ^
(b)
(c)
Y
PBr,
56. In the following reaction the major product is
o
, 0
OH
h3O+
(d)
„
HO N
o
(c)
cA = A, A
>
H3O+
Ph-C-H
O
OH
0s04
>
H30+ CH3MgBr
OH
o
O II
Mg/Et,0
^
OH OH
O
(b) HO
alc. K O H ^
cold. KMnQ 4 soln
HIO.
(b) 2,4-DNP (d) L/OH-.
(a) NaHC0 3 (c) NH 4 0H/AgN0 3
ANSWERS
1. 6. 11. 16. 21. 26. 31. 36. 41. 46. 51. 56.
(a) (a) (b) (b) (c) (d) (a) (d) (a) (b) (b) (b)
2. 7. 12. 17. 22. 27. 32. 37. 42. 47. 52. 57.
(a) (d) (d) (c) (b) (a) (a) (a) (b) (a) (d) (b)
3. 8. 13. 18. 23. 28. 33. 38. 43. 48. 53. 58.
'(c) (d) (b) (c) (b) (c) (b) (a) (a) (c) (c) (d)
4. 9. 14. 19. 24. 29. 34. 39. 44. 49. 54. 59.
(d) (c) (b) (c) (b) (a) B(OEt) 3 + 3HC1 BF3 Br 3 BNMe 3 (c) BBr + F,BNMe 3 BCI, + 2NMe 33 (d) BC1, CI 3 B(NMe 3 ) 2
(a) BF3 + 3C,H s Mgl
15. When XeF,4 is treated with water, it forms (b) both Xe and Xe0 3 (a) only Xe (d) both XeO,3 and XeOF,4 (c) only Xe0 3 16. Which of the following is the correct order of second ionization energy? (a) V > Cr > Mn (b) V < Cr < Mn (c) V < Cr > Mn (d) V > Cr < Mn 17. Which of the statement about the following structures is false? CI en en (1)
on
'Cr'
en
(a) (b) (c) (d)
>-" en I and either of the II and III are trans and c/s-isomers. I and II are enantiomers. II and III are optical isomers. I, II and 111 are isomers.
22. Which of the following will produce 2,4-dichloro phenoxy acetic acid, i.e., (2,4-D), a weedicide? OH PI (I) NaOH v C1 V (a) | + ClCH 2 COOH > (2)hc[
0 H
(b)
CI
-(c)
OH H U
(d)
CHEMISTRY TODAY|MARCH'08
(I) NaOH (2) HC'I
+ C1CH.COOH
(I) NaOH
+ C CH,COOH —1 2
+ CICH2COOH
( 2 ) HC1
.
>
(1) NaOH
v
>
(2) HC1
23. When C F 3 - C - 0 - 0 H is reacted with mesitylene O
q
Comprehension (Q.18-Q.21) : A green solid (A) is watersoluble and its solution gives a white precipitate of AgCl soluble in NH,. When NH 4 OH is added to green solution of (A), a green-precipitate (5) is formed. When (5) is boiled with Na z O, and water, a colour change to yellow results and solution (C) is obtained. Acidification of (C) causes the colour of the solution to change from yellow to orange solution (D). Addition of dilute aqueous Pb(NO,) 0 to the orange solution (D) produces a bright yellow precipitate (£) in alkaline medium.
(d) FeCI,
a
(1,3,5 trimethyl benzene) in the presence of BF,, the product formed is Me
Me
(a)
(b) Vic
Me
BF.,
Ol X
CH-CF,
Me
(c)
Me''
(d) 011
Me
Me'
H
Me C-CF, II O 15
reacts with Br,(«g). Ozonolysis of B produces a compound C.H s O,. Which of the following is structure ure of .4? ClLCIiCl C\ (a) (b) H,C CI -C3H3
O"
(c)
O I! CH, -C
i /OH"
II
The following flow-sheet diagram was prepared on the basis of the above reactions. Water soluble Unknown
I
(d)
5% NaHCO,
-CH,CH, TI Assertion (A) and Reason (R) Type questions
in the following questions (Q. 35-37), a statement of Assertion (A) is given followed by a corresponding s t a t e m e n t of Reason (R) j u s t below it. Of the statements, m a r k the correct a n s w e r (a) If both A and R are time and R is correct explanation of A. (b) If both A and R are true and R is not the correct explanation of A. (c) If A is true but R is false. (d) If A is false but R is true. 35. Assertion : CH = CH reacts with HCl in the presence of HgCI, while CH, = CH, does not. Reason : There is more unsaturation in CH = CH than in CH, = CH,. 36. Assertion : Unsubstituted alcohols give dehydration reaction only in acidic medium. Reason : If a strong base is used, then alcohols undergoes elimination reaction. 37. Assertion : Treatment of 1,3-dichloro propane on reaction with alcoholic KOH gives CH, = C = CH, \ Reason : It is nucleophilic elimination reaction.
-> CHIjxl + HCOO"
No reaction
r
Reaction
KMnOi
2,4-DNP
r
Reaction
No reaction
Fehling's test
Lucas • test
No immediate
Reaction
No
reaction
|
reaction]
| No immediate Reaction 1 reaction "
Reaction
I ' IV Iodoform test
VII
No reaction Reaction VI
V
38. Compound II should have (a) - COOH group (b) an alcoholic group (c) both (a) and (b) (d) a phenolic - OH group 39. Compound 111 is (a) C 6 H 5 OH (c) C H OH
(b) C H„OH (d) any of the three
40. Which of the following compound can be an aldehyde (a) V (b) VI (c) VII (d) IV 41. Compound V can be (a) CH 3 CHO (b) CH,COCH 3 (c) CH,ICOC,H. (d) any1 of the three SECTION B
42. Which of the following statements are correct? Comprehension (Q. 38-Q.41) : Characteristic reactions (a) the electronic configuration of Cr is [Ar] 3d54s' (At. no. of Cr = 24) of some of the important groups are given below (I) Phenols and carboxylic acids are soluble in dil. (b) the magnetic quantum number may have a negative NaOH, however only carboxylic acids are soluble value in very dilute (5%) aqueous NaHCO^ solution with j (c) in silver atom, 23 electrons have a spin of one type the evolution of CO, gas. and 24 of the opposite type (At. no. of Ag = 47) (II) Lower alcohols containing five or less carbon atoms i (d) the oxidation state of nitrogen in HN3 is - 3 . react with Lucas reagent, while the higher alcohols ; 43. Which of the following are true? do not react with the reagent. (a) In NaCl crystals, Na + ions are present in all the (III) Aldehydes and ketones reacts with 2 , 4 octahedral voids. dinitrophenylhydrazine to give orange coloured (b) In ZnS (zinc blende), Zn2+ ions are present in alternate crystals, however only aldehydes reduce Fehling tetrahedral voids. solution. (c) In CaF„ F" ions occupy all the tetrahedral voids. (IV) Acetaldehyde gives yellow precipitate with alkaline (dj In Na,0, 0 : ions occupy half the octahedral voids. iodine. 18
CHEMISTRY TODAY I APRIL '06
44. A compound A reacts with KI to form yellow ppt. B. It reacts with BaCI2 to form white ppt. C which is soluble in excess of NH, solution and forms D. A also reacts with NaOH to form brown ppt. E. Compound A and E are (a) AgN0 3 , AgOH (b) Pb(NO,)„ Pb(OH), (c) CuS0 4 , Cu(OH), (d) Ca(N0 3 ) 2 , Ca(OH)~ Comprehension (Q. 45-Q. 47) : There is negligible intermolecular force of attraction between gas molecules. Molecules are constantly moving in zig-zag motion colliding with each other as well as with walls of the container and exert pressure. The kinetic energy is directly proportional to absolute temperature. Different molecules move with different velocities at a particular temperature. When temperature is increased, the average velocity of molecules increases but distribution of velocities remain the same. 45. The velocity possessed by maximum number of molecules is called (a) average velocity (b) root mean square velocity (c) most probable velocity (d) none of these 46. The kinetic energy of 8 gm of O, at 300 K. is (a) 0.9353 kJ (b) 1.870 kJ (c) 3.74 kJ (d) 0.0935 kJ 47. The root mean square velocity is equal to 100 m/s. What would be average velocity? (a) 92.13 ms-1 (b) 101 ms"1 (c) 81.6 ms-' (d) 102 ms-' Comprehension (Q. 48- Q.50) : A spinel is a class of oxides in which two types of cations are present, bivalent cations and trivalent cations. Oxide ions are arranged in CCP layers Bivalent cation occupy l/8 ,h of the tetrahedral voids. Trivalent cation occupy 1/2 of the total number of octahedral voids. 48. If.4 is bivalent, B is trivalent cation, what is formula of oxide having spinel structure? (a) AB,0, (b) A 0 BO, (c) ABO, (d) A,BO 49. One trivalent ion will occupy the void formed by (a) six O 2 - ion (b) four 0 2 ~ ion 2 (c) three O - ion (d) eight oxide ions 50. I f — lies between 0.414 to 0.732, the cation will r occupy CHEMISTRY TODAY |MARCH'08
(a) trigonal void (c) octahedral void
(b) tetrahedral void (d) cubic void
51. Which of the following are optically active, optically inactive and which are coloured due to charge transfer spectra and which due to d —> d transition and which are colourless (1) [Fe(en),] 3+ (2) [Pt(NH 3 )(H,0)CI, Br]2+ (3) M(a — a') trans form (4) [Ti(H,0)J 4 + (5) [Ti(H,0)J 3 + (6) MnCV (7) Agl (a) (l)-optically active, (2)-opticalIy active (b) (l)-optically active, (2),(3)-optically inactive (c) [ T i ( H 2 0 ) J 4 + colourless, optically inactive, [Ti(H,0) 6 ] 3+ coloured due to d —> dtransition and optically inactive (d) (6), (7) coloured due to charge transfer 52. For the following conversions CI
01 NO,
Conversion A
o
NO,
Conversion B : NO,
NO,
(a) for conversion A, the steps in Z (i) aq. OH /A (ii) H + /H,0 (b) for conversion B, the steps in P (i) NH, + CuO/A (ii) C1-CH,CH,CH,-CH,-CH,-C1 (c) for conversion A, the steps in Z (i) aq. NaOH at -1000°C , (ii) H + /H,0 (d) for conversion B, the steps in P (i) f
YH
53.
H 2 /catalyst 1 atm 25"C
•> A
J
K.MnQ 4 H20/A
IN DENE H , /Catalyst 100 atm 100°C
C NH, V
B
D
In the following reaction sequence given (a) compound A is
19
(b) compound B
charged, hydrophobic and hydrophilic. Which is the correct classification of the following four amino acids?
" C OCOOH
(c) compound C is [
+
|
COOH
(I)
O
NH, I C 6 H 5 CH 2 CHCOO"
H
+
CH 2 -CH 3 alk. KMnOj
A + co2 H+/IL,0
+
H
B KMnOj J + CH,-C-0-C-CII, ' II II •' o o r p H+/H-°> O In the reaction sequence given for toluene, identify A, B, X, )', P, O . CH2COOK (a) A =
,B
COOK
(b)
COOH
-^.COOII
JQ^
/CI
(c) X = CH,-CHO
o
II
(D) P = I
I
,0-C-CH, ^O-C-CH, II O
CHO
Q =
Comprehension (Q.55-Q.59) : Amino acids contain an -NH^(basic) as well as a - COOH(acidic) group. They exist as zwitter ions. R R H,N-CH-COOH HJN-CH -COOwhich explain their several characteristic properties, like decomposition on heating, solubility in water, large dipole moment. Thus in solution, amino acids may exist as dipolar ion (neutral pH), cationic (in strongly acidic solution), or anionic (in strongly basic solution). Amino acids undergo usual reactions of the - COOH group as well as - NH, group. 55. At intracellular pH (-6—7), amino acids can be divided into four types positively charged, negatively 20
NH3
(IV) HOOCCH 2 C H - COO" (a) (I)-hydrophobic, (11)-+ vely charged, (III)- - vely charged, (IV)-hydrophilic (b) (I)-hydrophobic, (Il)-hydrophilic, (III)- + vely charged (IV)- - vely charged (c) (I)-hydorphilic, (Il)-hydrophobic, (111)- + vely charged (IV)- - vely charged (d) (I)- + vely charged, (II)- - vely charged, (111) hydrophobic, (IV)-hydrophilic 56. Amino acids are (a) as basic as a typical amine and as acidic as a carboxylic acid. (b) less basic than a typical amine and less acidic than a - COOH. (c) more basic than a typical amine and more acidic than a - COOH. (d) nothing is certain.
= Q r "
CH:
NH3 I I " (II) CH : , C H - C HCOO~
NH, I (III) H 2 N - ( C H 2 ) 3 - C H - C O O "
O X*
+
+
(d) compound D is
54.
OH
57. Base treatment of an amino acid usually results in the conversion of the acid to a derivative via the amino carboxylate salt. The above procedure (a) decreases the rate of electrophilic reaction of the free amino group. (b) decreases the rate of nucleophilic reaction of the free amino group. (c) enhances the rate of nucleophilic reaction of the free amino group. (d) enhance the rate of electrophilic reaction of the free amino group. 58. Benzoylation of an amino acid can best be done by treating the amino acid with benzoyl chloride (a) in presence of dil. NaOH (b) in presence of conc. NaOH (c) in absence of NaOH (d) in presence of HCl +
59.
NH, I R-CH-COO"
NH, pH » 12
^
R-CH-COO"
-> Z. Compound Z is CHEMISTRY TODAY I APRIL '06
+
NH, (a)
R - C H - COO
-
(b)
R-CH-COO'
(d)
NH, I R-CH-COOH
+
(c)
NH, i R-CH-COOH
NH3
60. Histidine, a heterocyclic amino acid has following structure at pH < 1.82, UN TL VCH,CHCOOH N II at pH > 1.82 it should have which structure? NH, I ' CH,CHCOO"
UN // (a)
5000
NH,3 I O - C H ; CHCOOl I
HN-T\ (b)
.(c)
(d)
I1N//
r \
Students will get I unfair advantage... I
NH, I -CH,CI 1COOH
Yes! w e are now offering the
NH, 1 -CH,CHCOOH
O n l i n e Training M o d u l e for the Preparation
H,
precise
ANSWERS 1. 6. II. 16. 21. 26. 31. 36. 41. 44. 49. 52. 55. 60.
22
CH, I ' • CH - CH3
(d)
9.
(b) : In nitrating mixture HN0 3 acts as a base as -
©
HO - NO, + 2H 2 S0 4
©
11,0+ + 2HS0 4 " + NO,
10. (c)
11. (d) : Highly electronegative fluorine atoms pull electrons strongly from sulphur and thus, lower its nucleophilic power and hence, it will have highest leaving ability. 0 F 1 4 O-S^C-^F I * o
F
12. (d)
13. (c) : Nitration involves the formation of an + electrophile i.e. NO, ion. 14. (c) : The peroxide effect does not apply to the addition of HCI. It proceeds with formation of more stable C H 3 - C H - C H 3 carbocation. 15. (c)
CH,
CH,
(ii) CH, - CH - CH - CH3 (iii) C H 3 - C H 2 - C - C H , CI (iv) CH, - CH2 - CH - CH3 CH,C1 Compounds (i) and (iii) have no chirai carbon atom and hence, they are optically inactive. Compounds (ii) and (iv) both have chirai carbon atoms and hence, they are optically active. Thus, the two pairs of enantiomers will be as H I CH, - C - CHMe2 I CI
8.
H Me2CH-C-CH3 CI
16. (b) : BaO, + H , S 0 4 BaS0 4 + H 2 0 , In the products electronegative element is oxygen. Hence, the oxidation state of O atom in BaS0 4 = - 2 and in H 2 0 2 = - 1 . 17. (b) : As, CP = 37.2 J, R = 8.3 J Now by applying the formula, CP - Cv = R => 37.2 — Cy= 8.3 .-. C|/ = 28.9. Since, y = £e- = — = 1.280 = 1.3. ' Cv 28.9 18. ( c ) : As the correction in ideal gas equation due to intermolecular forces of attraction is
y%
19.(b) : Given, P° = 200 mm, P = 195 mm w = 2.0 g, M= 78, W = 78, m = ?
enantiomers 38
CHEMISTRY TODAY
APRIL 06
Applying
P°-P
P° 200-195 200
26. (b) :
wM
CH3CHO
Wtn 2x78
200
78x/«
40 fl? '
m
C.2H5 CFI3 - C - OMgl — C 2 H 5 C H O H C H , + Mg(OH)I HCl
20. (a) : As, according to vant Hoff's equation, VI' nV = nRT => nV = — RT m wRT
21. (a) : N 2 0 4
o
OMgl
C H 3 - C - C H , + CH3MgI acetone
— > CH 3 - C - CH 3
Grignard reagent
CH 3 CH 3
HCl
> CH3 - C - OH + Mg(OH)I CH,
2NO,
1
tertiary alcohol
0
(1-0.2)
2 * 0.2
= 0.8
= 0.4
27. (d) : 2-methyIpropane-2-ol is OH
Now by substituting the values in V = 1.2x0.082x300 1 Now, density
secondary alcohol
H
Now, by substituting the values, we get 10x0.082x288 „„„ m = = 1198. (600/760) x 0.25
Finally
Grignard reagent
5 _ 2
m = 80.
Initially
C2H5MgI
acetaldehyde
nRT
CH, - C - CH,
CH3 It is a tertiary alcohol, tertiary alcohols react very fast with Lucas reagent (conc. HCl + ZnCl 2 ).
= 29.52 lit.
Mol. wt. Volume
92 29.52 (mol. wt. of N 2 0 4 = 92)
= 3.12 gm/lit. 22. (c) : As, K, =
K-, -
[S0 3 ] [ S 0 2 ] [ 0 2 ] 1/2 [SO 2 ] 2 [Q 2 ]
(ii)
[SO,] 2
It is clear from (i) and (ii) that K2 =
CH3 group has +ve inductive effect so
0,N
29. (b) :
>C^=0:
\
2S03te)
_.[n[P]^[0.4][1.0]__0.4^1 K r [A][B] [0.5][0.8] 0.4 .-. Kr = 1.0
35 CHEMISTRY TODAY|DECEMBER'05
Q
OH
nucleophile
(mol/lit) • = lit mol (mol/lit) 2 x (mol/lit)
^
r ® -
C—O,: + H + C N "
2
25. (b) : As, K(: for the equation A + B ^
~ O H
OH
> CH
24. (a) : As, for the reaction 2S02(k) + 0 2 ( s ) ^
3
•OH
2NOC1 (g)
2 K(.= [NOC1] 2 [N0] [C1 2 ]'
Kr=-
C H
will be weakest. Therefore, the correct sequence is
(K i)"
23. (b) : As the expression for Kc, for the reaction, 2 N 0 W + C1 2 W ^
28. (d): Phenol is acidic in nature due to extra stability of phenoxide ion (C 6 H 5 0~) due to resonance. Acidic strength of phenol increases if a group or atom having - v e inductive effect is attached to the ring. e.g. - CH 3 , - C 2 H 5 etc. Since - NO, group is stronger electron attracting as compared to - OH group. So nitrophenol will be strongest.
— > C +D
> 9 - OH CN cyanohydrin
So, it is a nucleophilic addition. 30. (c) : RCHO + 2CuO (Fehling . solution)
> RCOOH + Cu,Oi (red ppt.) 47
31. (a) : The structure of bleaching powder molecule is Ca /\
CI Oui
The CI attached to Ca has oxidation number - 1 and that which is attached to O atom has +1 oxidation number as electronegativity of O is greater than CI. Thus, the resultant oxidation number of CI
+1+H)
• = o.
32. (c) : C102~ ion involves sp1 hybridisation in chlorine atom and has given structure.
41. (c) : Boiling point is a colligative property which depends upon the number of particles. 42. (c) : When 180 g of glucose is dissolved in 1000 g of water, the solution is said to 1 molal. v 500 g contains 18 g glucose 18x1000 _ 1000 g contains — — — = 36 g 500 180 g in 1000 g means m solution mxI
= 0.2 m.
180 5 4 3 . ' ( b ) : HC0 3 " behaves both as Bronsted acid and Bronsted base as HC0 3 " H + + C0 3 2 " bronsted acid
Thus the structure of CIOY is
bronsted base
angular.
44. (c)
33. (d) : In all three compounds, the oxidation number of iodine is +7. 34. (d) : Arsenic forms two oxyacida H 3 AsQ 3 and H 3 AS0 4 . Antimony forms only one cxvaeid H 3 SbO,. Bismuth forms only one oxvacid i.e. metabismuthic acid HBi0 3 (Scarlet red solid). 35. (a) : H 4 N 2 0 4 is known as niiioxylic acid or hydronitrous acid. It is supposed to be hydrate of nitric oxide, 2NO 2 H 2 0 . Ktn„c, it» anhydride is NO. A
36. (b) : H O - C H 2 - C H , C O O H
R> CH : = CH.COOH acrylic acid
[3-hydroxypropionic acid
37. (c)
mx 36
36 g in 1000 g means
COONH 4
I COON1 !4
P..O, -2H20
ammonium oxalate
CONH,
CN
P,O 5
CONH 2 "
2H
:°
CN cyanogen
oxamide
38. (c) : Cyanic acid exhibits tautomerism as H - 0 - C = N
;=±H-N =
cyanic acid
39. (d) 40. (c) : Oxalate ion forms chelate compounds with metals. The chelates are actually complex compounds in which closed rings are formed.
'
O— C—O
>
V I 2
M-C
^
COOH
s o
90°C
H,0 + CO + CO,
oxalic acid
46. (d): The solubility products of different hydroxides in question are given as : Cr(OH) 2 = 1 x 10"17 Cr(OH) 3 = 1 x 10"33 16 Fe(OH) 2 = 8 x 10~ Fe(OH) 3 = 4 x 10"40 As the solubility product of Fe(OH) 3 is lowest and therefore, Fe3+ will require lowest concentration of OH" ions for the precipitation as Fe(OH) 3 . 47. (a) : The standard heats of formation of chlorides of alkali metals are as: NaCl = - 400 kJ m o l 1 , KC1 = - 428 kJ mol-' RbCI = - 423 kJ mol"1, CsCl = - 424 kJ mol"' Hence, sequence of thermal stability will be as KC1 > CsCl > RbCI > NaCl 48. ( d ) : Given, A7>= - 0.150°C, KF = 1.50, KH = 0.41 A7}= Kj x molality (m) Molality (m)
AT,
0.150 .50
= 0.1 m
ATH = KH x molality (M) = 0.41 x 0.1 = 0.041°C. 49. (a):
CH,-CH2-CH,-CH3n-butyl benzene
— 0n2_
X0 - C = 0
conc. H
COOH
C = 0
isocyanic acid
o = c-o. > I V
45. (d) :
hot K M n O
(OTCOOH+co, benzoic acid
Five membered rings are formed.
50. (d) : Carbonyl compounds (aldehydes or ketones) form cyanohydrin on reacting with HCN.
40
150
CHEMISTRY TODAY I APRIL '06
It is a nucleophilic addition reaction which proceeds by attack of nucleophile. (: CN" ion). \ / C
I. - C - CN I
H+ >
-C-CN
o-
: CN
OH cyanoliydrin
+ : NH2OH
-
H
oxt me
52. (b) : For the reaction, 2 S 0 2 + O,
2S0 3
[S0 3 ] 2 [so2fto2] 1 - = conc. [mol/lit]
[mol/Iit]2[mol/lit]
4x-W[fif [Af[3f H + + OH"
According to law of mass action,
/ C = NOH + H,0
[mol/lit]2
-
-\B? 8L J
60. (c) : H 2 0
ketone
Kc =
~ 4[A]2
Hence, rate of reaction will become half of initial rate.
-C-NHOH I OH
hydroxy! amine
o
2
1
51. (c) : Oximes are formed as :
\ / c
roc [2A]2
53. (c)
[H + ][OH~] ionization constant of water, K = [H 2 0] As water is very less ionized the value of H 2 0 remains almost constant and hence £ [ H 2 0 ] = [H + ][OH"] K[U20] = Kw = [H + ][OH-] K = o r , [H 2 0]
K =
55.4 [H 2 0] = 55.4 mole/litre]
54. (d) : When benzaldehyde is refluxed in presence of NaCN or KCN, benzoin is formed. H I benzaldehyde
O II
KCN
benzaldehyde
H O I II OH benzoin
55. (d) : The amino acids which have one carboxylic acid group and one amino group behave as a neutral compound. This is due to the fact that amino and carboxylic groups, being of opposite character neutralize one another intramolecularly and form an internal salt. Thus, in aqueous solution a-amino acids behave as salt. 56. (c) 57. (d) 58. (b) : Energy of first Bohr orbit of hydrogen is Z2 1 E, =-13.6x——eV = - 1 3 . 6 x - = -13.6 eV ' n2 1 and energy of third Bohr orbit is \ E3 =-13.6X4T eV = -1.5 eV. 3 59. (a) : Reaction \2A + 3B r oc [A]2 [5]3 CHEMISTRY TODAY | APRIL 06
2C + 5D
Based on Latest Pattern • 10 Very Similar Practice Test Papers • 2002-2005 Expert's Solved Papers • 2000+ MCQ's with detailed Solutions • Frequently Asked Questions oj^M ^ f Rs.200 % ^,pages.1ioo$
41
(AIIMS
; C B S E ] (D P M T ) ( A F M C ] ( V M M C ) (EAMCET) (W B - J E E ) ( B H U
) ( CMC )
2006 Medical Entrance Exam ( UP CPMT ) (CET Karnataka MP PMT) M G I M S
Practice Test Paper
2. 5.6 g of a metal forms 12.7 g of metal chloride. Hence, equivalent weight of metal is (a) 127 (b) 254 (c) 56 (d) 28. 3. Mole fraction of ethanol in ethanol-water mixture is 0.25. Hence, percentage concentration of ethanol by weight of mixture is (a) 25% (b) 75% (c) 46% (d) 54%. +
When N 2 changes to N 2 , the N - N bond distance and when 0 2 changes to 0 2 + , O - O bond distance (a) increases, decreases (b) decreases, increases (c) increases in both cases (d) decreases in both cases. 5. In which there is change in the type of hybridisation when (a) NH, combines with H + (b) A1H, combines with H (c) in both cases (d) none of these. 6. Hypervalent compound is (a) S0 3 2 (b) P0 4 3 2 (c) S0 4 ~ (d) all are correct. 7. The correct order of increasing C - O bond length of CO, CO,2", CO z is (a) C0 3 2 - < C 0 2 < CO (b) C0 2 < C0 3 2 ~ < CO (c) CO < C0 3 2 " < C 0 2 (d) CO < C 0 2 < C0 3 2 -. 8. Amongst Ni(CO) 4 , [Ni(CN)4]2~ and NiCl 4 2 " (a) Ni(CO)4 and NiCl42" are diamagnetic and [Ni(CN).,]2 is paramagnetic (b) NiCl42" and [Ni(CN)4]2~ are diamagnetic and Ni(CO)4 is paramagnetic 50
( JIPMER
)
PMDT B i h a r ) fPMT HaryanlTj ( K e r a l a P M T ) ( R a j . P M T ] f T N P C E E )
1. Sulphuryl chloride S02C12 reacts with water to give a mixture of H 2 S0 4 and HC1. Mole of NaOH required to neutralise the solution formed by adding 1 mole of S02C12 to excess water is (a) T (b) 2 (c) 3 (d) 4.
4.
(Manipal PMTj
(c) Ni(CO)4 and [Ni(CN)4]2~ are diamagnetic and NiCl42~ is paramagnetic (d) Ni(CO)4 is diamagnetic and NiCl 4 2 -and [Ni(CN)4]2" are paramagnetic. 9. COC13-4H,0 is an anhydrous binary solute. Hence, its Werner's representation is CI CI | OH, | OH, (a) C l - C o - O H , (b) CI — Co — OH, H2O q OH2" H 2 0 £[ OH2 CI OH2 \ l (c) H,0 — CoI — OH, C1
(d) none of these.
OH>
10. KMn0 4 oxidises X n + into X0 3 ~, itself changing to Mn2+ in acid solution. 2.68 x 10~3 mol of X"* require 1.61 x l o - 3 mol of Mn0 4 ". Hence value of n is (a) 2 (b) 3 (c) 4 (d) 0. I 11. In Aufbau rule is not used, 19th electron in Sc ( Z = 21) will have (a) n = 3, / = 0 (b) n = 3, / = 1 (c) n = 3, / = 2 (d) n = 4, 1= 0. 12. The compressibility factor of gas is less than unity at STP, therefore (a) V,„ (molar volume) > 22.4 lit (b) Vm< 22.4 lit (c) Vm = 22.4 lit (d) Vm = 44.8 lit. 13. Which gas shows real behaviour? (a) 8 g O, at STP occupies 5.6 litre (b) 1 g H, in 0.5 L flask exerts a pressure of 24.63 atm at 300 K (c) 1 mol NH 3 at 300 K and 1 atm occupies volume 22.4 litre (d) 5.6 litre of C0 2 at STP is equal to 11 g. 14. For the non-zero value of froce of attraction between gas molecules, gas equation will be C H E M I S T R Y T O D A YJANUARY'06
(a) - 4 3 . 3 (a)
PV = nRT
(b) PV= nRT + nbP
—V
(d)
(c) PV - nRT
P=
n R T
V-b
:A 15. FeCIj on reaction with K 4 [Fe(CN) s ] inaq. K,[Fe(CN 0.01 M FeCI,= solution gives blue colour. These are side A' ; ; ; ; ; side Y I EE separated by a B semipermeable membrane A B as shown in figure. Due to osmosis there is (a) blue colour formation in side X (b) blue colour formation in side Y (c) blue colour formation in both of sides X and Y (d) no blue colour formation.
16. See the table. A+ B-^ 1 2 3
C
[A]
IB]
[rate]
1.0 2.0 1.0
1.0 1.0 2.0
0.25 0.50 0.25
-1
(c) + 6 . 2
17. Rate constant of a reaction is 0.0693 min"1. Starting with 10 mol, rate of the reaction after 10 min is (a) 0.693 mol min' 1 (b) 0.0693 mol min' 1 1 (c) 0.0693 x 5 mol min' (d) 0.0693 x (5)2 mol m i n - i . 7 18. If Ag + 2NH 3 = Ag(NH 3 ) 2 , K, = 1.8 x 10 + 9 Ag + CI' = AgCl, K2 = 5.6 x io then for AgCl + 2NH, = Ag(NH 3 ) 2 + + CI', equilibrium constant K will be (a) 0.32 x 10' 2 (b) 0.31 x 103 17 (c) 1.00 x 10 (d) 1.00 x 10' 17 .
(d) + 1 0 . 3
20. The dissociation energies of CH 4 and C,H 6 to convert them into gaseous atoms are 360 and 620 kcal mol"1 respectively. The bond energy of C - C bond is (a) 260 kcal mol"1 (b) 180 kcal mol"1 1 (c) 130 kcal mol" (d) 80 kcal mol' 1 . 21. In the reaction : [A1(H,0) 6 ] 3+ + H , 0 = [A1(H 2 0) 5 ] 2+ + H 3 0 + (a) [A1(H,0) 6 ] 3+ is a base (b) [A1(H,0) 6 ] 3+ is an acid (c) both are correct (d) none is correct. 22. pH of Ca(OH) 2 is 12. Milliequivalents of Ca(OH) 2 present in 100 mL solution will be (a) 1 (b) 0.5 (c) 0.05 (d) 5. 23. For the first order reaction A —> product, the halflife time is 100 seconds. The rate constant of the reaction is (a) 6.93 x I0"2 s' 1 (b) 6.93 x 10"4 s' 1 3 1 (c) 6.93 x 10' s" (d) 6.93 s' 1 . 24. Maximum enolisation takes place of (a) CH 3 COCH 3 (b) CH 3 COCH 2 CHO (c) CH 3 COCH 2 COCH 3
(d)
1
Rate is expressed in mol lit min' . In the above reaction, the order is (a) zero in A and one in B (b) one in A and zero in B (c) one in both A and B (d) zero in both A and B.
+
(b) - 1 0 . 3
O
o
25. Type of isomerism shown by the product of the reaction between benzaldehyde and hydroxy! amine is (a) syn and anti geometrical (b) cis and trans geometrical (c) E and Z geometrical (d) none of these. 26. Most stable free radical is (a) CH, — CH (c)
(b) CH, = CHCH, CH,
CH3
(d)
+
19. Using only the following data, I. Fe,0 3 (,) + 3CO f e ) = 2Fe„., + 3CO 20r) , AH° =-26.8 kJ II. Fe (5) + CO, = FeO (.s) + CO te), AH° = 16.5 kJ. TheA//° value, in kilojoules, for the reaction III. F e2,W03 (.v) CO fe) 2FeO co 22 fe) is calculated to be 35 CHEMISTRY TODAY|DECEMBER'05
27. Major product of the following S N 1 reaction is CH, - CH - CH - CH, + OC,H, > 3 3 2 5 I I Br CH, CH3 I (a) CH3CHCHCH3 (b) CH,CHCH,CH,OC 2 H 5 OC,H, CH, (c) CH3CH,CCH3
CH, (d) none of these.
OC2H5 47
46. EN o f the e l e m e n t s is £ , and ionisation potential is E2. H e n c e energy o f activation will be (a) 2 £ , - E2 (b) £ , - E2 (d) (£, - E2)/2. (c) E, - 2E2 47. Stability order o f + 3 and +1 states o f II1A (boron family) element is (a) Ga 3 + < In 3+ < Tl 3 + (b) Ga + > In + > Tl + +
+
(c) Ga < ln < Tl
+
(d) Ga
3+
f Bond length oc ! V bond order Hence, N 2 —> N , + , bond length increases. O , —» 0 2 + , bond length decreases.
5.
(b) : N H , sp
< Ga .
A1H3
each P is j o i n e d to four P each P is j o i n e d to three P each P is j o i n e d to t w o P P 4 d o e s not exist.
B AIH4
sp2
49. A g , S + N a C N A + Zn - » B is a metal. Hence, A and B are (b) N a [ A g ( C N ) 2 ] , A g (a) N a , [ Z n ( C N ) 4 ] , Zn (d) N a 3 [ A g ( C N ) 4 ] , Ag. (c) N a [ A g ( C N ) 4 ] , A g 50.
sp'
+
48. In P 4 (tetrahedral) (a) (b) (c) (d)
•NH4
——— = z < 1
RT
P and T remains constant is less than 2 2 . 4 litres.
Vm (molar v o l u m e )
13. (c) : If gas is real, then PV * 14. ( a ) :
P+-
nRT.
[V - nb] = nRT
35
If force of attraction exists then nb = 0. P+- 2 V
V = nRT .
P V +
l l V
= nRT,
15. (d) : Osmosis of solvent takes place hence, no interaction between solute particles.
24. (d) :
OH
25. (a) :
is most stable due to resonance.
CHO + NH2OH
> CH = N - OH
dx 16. ( b ) : y - } = k[AY[BX If concentration of the reactant is made m times, rate becomes m" times for «,h order reaction. From (i) and (ii), if concentration of A is doubled rate is also doubled. Hence 2" = 2 a = 1. From (i) and (iii), if concentration of B is doubled, rate remains unchanged. Hence, 2b = 1 => b = 0.
Benzaldoxime shows syn and anti geometrical isomerism. 26. (d) : Stability of free radicals - 1° < 2° < 3°. 27. (c) : CH,CHCHCH,3 ! 1 Br CH,
= k(A) = k(a-x)
= 0.0693 x 5 mol min"1.
18. (a) : K = — = 0.32x10" 2 . k2 19. (c) : I +
2(11)
= III.
20. (d) : [CH 4 —> C (g) + 4H ^ 1
1,2 H~ shift
10~2 xlOO - = 10" 1000 Milli equivalent = 10"3 x 1000 = 1.
Ca(OH) 2 =
23. (c) : Rate of half-time = k=
50
0.693
100
CH,
28. (b) : By 1,2-methyl shift, 2° carbocation changes to 3° carbocation. [Substituted alkenes are more stable], 29. (c) : Aldehydes/ketones with atleast one a - H give aldol condensation reaction. 30. (a) : Product due to ozonolysis is malonic acid CH 2 (COOH) 2 which is decarboxylated to CH 3 COOH on heating. Decarboxylation takes place in : * If two - COOH groups on same C. f 0 If there is
Hence, (BE) C _ C = 80 kcal.
Hence, in 100 ml solution equivalent of
CH.CHXCH
CH3
( B E ) C ^ C + 6 ( B E ) C _ H = 620 kcal
22. (a) : pH = 1 2 . pOH = 2 . [OH"] = IO"2 N = [Ca(OH)2]
OC2H5
OC2H5 .
3° carbocation
+ 6H Q,) ]
21. (b) : [A1(H 2 0) 6 ] 3+ changes to [A1(H,0) 5 0H] 2+ by loss of H + hence, it is an acid.
|
CH,
> CH,CH,CCH, 3 21 3
4 ( B E ) C _ H = 360 kcal
[C2H6 —» 2C
• ©
2° carbocation
17. ( c ) : k = 0.0693 min -1 (first order since unit of k is time"1). 0.693 = 10 min. T =If initial concentration is 10 mol, after 10 minute = 5 mol (50% reacted)
CH,CHCHCH,
*
^
- C - CH,COOH
p
v
"
/
keto group at
3-position If there is ( - C = CCH2COOH), double bond at P, v p y position.
31. (c): Fehling test is used to detect the reducing and non-reducing sugars. It reduces the glucose but not the sucrose.
J
0.693
= 0 . 6 9 3 X L 0 " Z = 6 . 9 3 X IO" 3 s"
32. (b) : CH 3 CH,CN -> CH 3 CH 2 NH 2 (one C less)
33. (d) : All the given ions are isoelectronic (each having ten electrons). For such cases, (RH °= 1/Z). Hence, Mg2+ < Na + < F~ < O2". Z=
(12)
(11)
(9)
(8)
34. (b) : KNO, + CH 3 COOH
HNO,
CHEMISTRY TODAYJANUARY'06
HNO, is complexing agent as well as oxidising agent for Co 2+ . Co2+ 35. (d) :
NO,-
Fe
Co
, 3+
3+
deep yellow
NO,-
[CO(NO,) 6 ] 3 "
^
Fe
2+
36. (b) : CCI,CHO is hydrated since hydrate formed is stable due to intramolecular H-bonding. CI H\
1
J
IS
electron withdrawing.
44. (b): If there is at least one a - H, KMn0 4 oxidation of alkyl benzene gives benzoic acid. If no a - H, then under vigorous oxidation by KMn0 4 , ring is cleaved, a - H present :
N
/
H^
o
(chloral hydrate) 37. (a) : CI is best leaving group. 38. (a) :
1 X 10~ = 27s
(b) M(OH),
1
(c) MOH
1 x IO"30 = s2
27 1x10"
io- 32 = As2
4
VlxlQ- 3 "
(d) MOH Most soluble is thus (a).
VlxlO"2*
39. (d) : For dilute solution, relative decrease in V.P. P°~P = x >h .. >h P n, + n2 n2 n| (moles of solute), /?, (moles of solvent) ii' g solute (mol. wt. = m) is dissolved in solvents (V.P. of pure A = p°A) ii'/ M w M. PA - P w,/M. M w. ii' M„ w M H P, -P Similarly, m n' =
which gives MA = 2 MH H Eu
+ Eu+
< Q > - C(CH3)3
46. ( a ) : (EN)={'F)
+ {EA)
CaSiF 6 + 3H,0.
(Mullikan scale)
2
47. (c) : By inert pair effect, stability of higher states decreases and that of lower state increases while going down the group in p-block elements (starting from fourth period). P
48. (b) : P
49. (b) : Ag 2 S + 4NaCN - 4 2Na[Ag(CN),] + Na,S A 2Na[Ag(CN),] + Zn Na,[Zn(CN) 4 ] + 2Ag B 50. ( d ) :
Rv
/ R
/ C = C ^
H"
H
( a complex)
59 CHEMISTRY TODAY |DECEMBER'05
> (CH3)3C • COOH
45. (a) : /, < I 2 « < /3 (very high) After two electrons have been removed, removal of third electron requires very big ionisation potential (1500 eV). Hence M 2+ has stable inert gas configuration.
, Lindlar
«
H
Li/NH3 ^
41. (b) : CaH, + 2 H , 0 -> Ca(OH) 2 + 2H,. 42. (b) : CaSiO, + 6HF glass
I O
1x10"
4
(a) M(OH),
x
|
a - H absent : Solubility (s)
33
Mn04 ^
CH(CH3),
K,,
Species
< Q > - CH2CH,
C —H
CI
40. (b) :
CH, > CCH,
( O ^ C . L ,
Cl-C
B„t
0
VCH3C
light green
O
43. (d) : CH3C f
SnCl 2 , Zn and H,S all reduce Fe3+ to Fe2+.
\
O
R-C = C-R HR/
C=C trans-
-H
is cis and II is trans.
47
S8PLE S W . E R f o r
| IIT-JEE 2006 will be negative marking in these
(For Q.No. 1 to 40) Only one option is correct 1. The hybridisation of iodine in iodosobenzene is (a) sp (b) sp2 3 (c) sp (d) sp3d. 2. (a) (c) (d)
Which of the following pairs is not isomorphous? BaS0 4 , KMn0 4 (b) KC10 4 , KBF4 FeS0 4 -7H,0, MgS0 4 -7H,0 NaCIOj, NaNO,.
3. Which of the following is correct order for solubility in water? (a) NaCI0 4 < KCI0 4 (b) NaBF 4 > NaF (c) MgS0 4 < SrS0 4 (d) all of these. 4. the (a) (b)
Which of the following can be best explained on basis of hydration of ions? Mg(C10 4 ) 2 is a powerful water absorbent LiC104 forms a stable hydrate but other alkali metals perch lorates do not (c) electrical conductivity of Li+ in aqueous solution is much less than expected (d) all of these. 5. In which of the following N atom is not sp2 hybridised?
(a) HN0 4
(b) FNOj
(c)
(d) B 3 N 3 H 6 .
NH2
6. In which of the following Xe atom is sp3cf hybridised? (a) [XeOh]4~ (b) [XeF3]+ (c) Xe0 4 (d) XeF2. 7. (a) (b) (c) (d)
Which of the following is correct statement? diamond is a good conductor of heat ozonide ion is diamagnetic hydroazoic acid is a linear molecule none of the above.
questions)
8. Which of the following orbital overlappings is not possible according to VBT?
(o
O C E X D
(d) all of these. 9. (a) (b) (c) (d)
Which is correct regarding the cyclic trimer of S0 3 ? it contains three S - S, o bonds it contains three O - O, o bonds it contains six O - O, ji bonds the total number of a and n bonds in it are 12 and 16 respectively.
10. Which of the following species does not exist? (a) Cl 4 (b) [Si0 4 ] 4 4 (c) [CO,] " (d) C 2 11. Which of the following is expected to have resultant dipole moment equal to zero? (a) H 2 0 2 (b) 0 3 (c) S0 2 (d) XeF4. 12. is (a) (b) (c) (d)
The correct order of sulphur-oxygen bond length SOF2 > SOCl 2 > SOBr, SOCl2 > SOBr2 > SOF2 SOF2 = SOCl 2 = SOBr2 SOBr2 > SOCI2 > SOF,.
13. Which is correct statement? (a) the B r P B r bond angle must be nearly 120° in the molecule PBr2CI3 (b) bond angle in PF3 is more than in NF 3 (c) bond angle in PH3 is more than in NH 3 (d) none of these.
Contributed by Deptt. of Chemistry, R e s o n a n c e , Kota (Rajasthan)
10
CHEMISTRY TODAY | JANUARY '06
14. A m o n g the following compounds the one that is polar and has central atom with sp3 hybridisation is (a) H 2 CO, (b) SiF 4 (c) BF,
0)
[
J
c
(d) HC10 2 .
COOH
- a
15. Which of the following is ionic? (a) KHF, (.,) (b) CaC 2( . 5) (c) PCI 5( . t)
(c) equal for both
O (H)- O - O - S - O -(H)
(Q)
a»
(Qj
(c)
CqJ
(d)
[QJ
II O
21. The end product o f the following reaction would be
R
which H will be released first as H + ? (a) a (b) 3
C,H,0H/HgS04/H®
CH 3 - C = C - H — — (a)
(c) both together (d) above acid is not possible. 18. According to VSEPR theory in [I0 2 F 2 ]" ion the F 1 F (a)
120°
(b) 90°
(c)
109° 28'
(d)
H CH-CH,
isomerisation
(a)
(b)
(c)
(d)
XZ
u^
0
(a) , (c)
H
(d)
[Xc „.
' CH 2 - CH - CH3
p j > - CH = CH - CH3 OH CH,-CH3
2 0 . The product III o f the following reaction sequence is
CH - O - CH2 - CH3.
22. Which route is appropriate for the f o l l o w i n g conversion reaction? .CHO ^ XHO
"CH-CH2-CH3
10 CHEMISTRY TODAY | JANUARY '06
C H 3 - C H 2 - O - C = CH,
O CH, - CH,
O
CH 3
(d) C H 3 - C H =
19. The least stable carbocation intermediate o f the following acid catalysed isomerisation reaction would be
>
V
(b) C H 3 - C H , - O - C H 2 - CH =
(c)
180°.
—
H,C-CH-CH3
bond angle will be nearly
CH =
^.COOH
^
11
OH
+ (II)
( Hi)
(«)
17. According to structure o f H 2 SO s ,
a
gBr )
. ^ ^ C H , - COOH
(d) nothing can be said.
^
PhM
(ii) (H)
(d) all o f these.
16. Dipole moment is higher for (a) CH,F (b) CD 3 F
X'
(I) (+2HCOOH)
= C H
C6H,C03H 5
(1)
3
N
NaOH
> —^r^ (2)
alkaline K M n 0 4
,,,
(I)
H,0
— ^ (2)
H,0
(i>
Br,
NaOH
(1)
(2)
*
(b)
H
0s04
:>
23. Which statement is correct about the f o l l o w i n g reaction? CH, - C H = CH2
NOCKnitmsyl chloride^
^
tautomerises
^
^
(a) X and Y do not have stereoisomers (b) X i s a racemic mixture, Y is optically inactive achiral compound (c) A'is mixture o f two stereoisomers and Kis a mixture o f four stereoisomers
I
(d) the electrophile is CI® ion in the above addition reaction. 24. The correct statement about the following reaction is Br Br 2 /CCl 4(l e q) ^ = 1 _ CH,-C = C-CH3 (1)
Br
27. In which case ar alkene is formed on reaction with a strong anionic base? H
(a)
(b)
(c)
(d)
(in
Cl Br C
'2/CCS
CH3-C-C-CH3 Br CI
(a) (b) (c) (d)
([V) dihalide
(III) (excess) but-2-yne is more reactive than but-2-ene towards bromine solution rate of addition of Cl, to (11) is faster as compared to but-2-ene the product (III) is a mixture of two enantiomers Cl I IV is C H , - C = C - C H 3 + ZnBr,. Cl
25. Four reagents (I, II. Ill and IV) are added to two compounds R and S. R responded positively to all reagents while S responded negatively to all reagents. The reagents are I. AgN0 3 + NH 4 OH (II) Br,/CCI 4 III. CH,MgBr (IV) alkaline KMn0 4 . R and S are respectively be (a) CH 3 CH, (b) CH, CH,
- CH 2 - CH, - C = CH and - CH 2 - CH, - CH = CH, = CH - CH : - OH and - CH, - CH, - CH : - CH 3
(c)
i^lj
and
^
(d) CH 3 - CH, - CH, - C = CH and CH 3 - CH, - O - CH, - CH,. 26. Dehydrohalogenation by a strong base is slowest in Cl Cl CII .Cl
(a)
(c)
' , Cl Cl Cl. CI
(b) Cl Cl
Cl
CI CI
(d)
Cl 28. The product X of the following sequence mainly exists in enolic form. The enol is C H , = C— CH,
NaNH2/NH3 (/)
CH3COCl HgS04/H,S04/H,0
> A'
(a) CH 2 — C - C H , - C - C H 3 OH
' 0
(b)
C H 3 - C = C H - C - C H 33 I II OH 0
(c)
CH = CH - CH, - C - CH3
(d)
OH O CH2=C-CH,-C=CH, OH
OH
The following questions consist of two statements one labelled Assertion (A) and the other labelled Reason (R). Select the correct a n s w e r s to these questions from the codes given below.
(a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. 29. Assertion : Both MeOH/H® and MeOH/Br,/H® give electrophilic addition reaction to R - CH = CH, type of alkene according to Markownikof's rule. The products are an ether and a (3-bromoether respectively. Reason : In both the cases, the electrophile H® ion adds to that side of double bond which has more number of hydrogen atoms. 30. Assertion : Rate of catalytic hydrogenation is faster CHEMISTRY TODAY
JANUARY
but rate of electrophilic addition is slower in ethyne as compared to ethene. Reason : Due to linear shape of ethyne its rate of adsorption at the surface of metal catalyst is faster than ethene for catalytic hydrogenation but the intermediate vinylic carbocation is less stable than ethyl carbocation in electrophilic addition. P A S S A G E 1 : Read the following passage and answer the questions numbered 31 to 35. T h e y have only one correct option.
All the boron trihalides except Bl3 may be prepared by direct reaction between the elements. Boron trihalides consist of trigonal-planar BX3 molecules. Unlike the halides of the other elements in the group they are monomeric in the gas, liquid and solid states, BF3 and BC1, are gases, BBr 3 is a volatile liquid and BI3 is a solid. Boron trihalides are Lewis acids because they form Lewis complexes with suitable bases, as in the reaction. BF3W+ :NH30rt-> F3B-NH3W However, boron chlorides, bromides and iodides are susceptible (sensitive) to protolysis by mild proton sources such as water, alcohols and even amines for example BCI, undergoes rapid hydrolysis. BC13 (x) + 3H 2 0 (/) B(OH)3 Uut) + 3HCI BC13 > BBr 3 (b) BF3 = BCI3 = BBr3 (c) BF, < BCI3 < BBr3 (d) BBr3 > BF, > BCI,. 32. Which of the following is the correct prediction about observed B - X bond length, in BX3 molecule? (a) B - F bond length in BF3 is found to be less than theoretical value because the electronegativity values of B (2.04) and F (4.0) suggest the bond to be ionic and hence the attraction between oppositely charged ions must decrease the bond length (b) BF, and [BF4] have equal B - F bond length (c) the decrease in the B - F bond length in BF3 is due to delocalised pn - pn bonding between vacant 2p orbital of B and filled 2p orbital of F (d) the correct B - X bond length order is B - F > B - CI > B - Br > B - I. C H E M I S T R Y T O D A Y |FEBRUARY'06
33. Which is correct about the hydrolysis of BX,? (a) all BX3 undergo hydrolysis to produce B(OH) 3 im/) and HX (H(/) (b) BF3 does not undergo complete hydrolysis due to formation of HBF4 (c) BBr3 does not undergo hydrolysis at all because it cannot form H-bonds with water (d) all the above are correct. 34. (a) (b) (c) (d)
Which of the following reactions is incorrect? BF3 (x) +. F~ (n \ / (CH3COO")2 (b) Hg . H,0 O,, A (c) CH3 - CH = CHMgBr -
NaBH,
V 7 THF (d) CHj - CH 2 -CH 2 MgBr ——^ > 55. When neopentyl alcohol is treated with H 2 S0 4 a mixture of two alkenes (85 : 15) is formed. Which statement/s is/are correct about these alkenes? (a) both give same majour product with HBr (b) both give different products (major) with HBr/R 2 0 2 / light (c) the alkene which is formed in 85% concentration has higher heat of hydrogenation than the other
one obtained in 15% concentration (d) both give same product on ozonolysis. ANSWERS
1. 6. 11. 16. 21. 26. 31. 36. 41. 43. 46. 49. 52. 54.
2. (c) 7. (a) 12. (d) 17. (b) 22. (c) 27, (c) 32. (c) 37. (b) (a, b, d) (a, b, c) (b, c) (b, d) 50. (a, b, c, d) (a, b, d)
3. 8. 13. 18. 23. 28. 33. 38. 42. 44. 47. (a, c, d) 53. 55.
(d) (a) (a) (b) (b) (b) (c) (b)
4. (d) 5. (b) 9. (d) 10. (d) 14. (d) 15. (a) 19. (c) 20. (d) 24. (d) 25. (c) 29. (c) 30. (b) 34. (d) 35. (b) 39. (d) 40. (c) (b, c, d) (a, b) 45. (d) (c, d) 48. (a, b, c, d) 51. (b, d) (a, c, d) (a, b)
(c) (c) (d) (b) (d) (a) (a) (b)
Note : For detailed solutions please log on to our website www.resonance.ac.in
Can We Drink Too Much Water? Q. Can w e R e a l l y D r i n k T o o M u c h Water?
In a word, yes. Drinking too much water can lead to a condition known as water intoxication and to a related problem resulting from the dilution of sodium in the body, hyponatremia. Water intoxication is most commonly seen in infants under six months of age and sometimes in athletes. A baby can get water intoxication as a result of drinking several bottles of water a day or from drinking infant formula that has been diluted too much. Water intoxication and hyponatremia result when a dehydrated person drinks too much water without the accompanying electrolytes. Q. W h a t H a p p e n s D u r i n g Water Intoxication?
When too much water enters the body's cells, the tissues swell with the excess fluid. Our cells maintain a specific concentration gradient, so excess water outside the cells (the serum) draws sodium from within the cells out into the serum in an attempt to re-establish the necessary concentration. As more water accumulates, the serum sodium concentration drops — a-condition known as hyponatremia. The other way cells try to regain the electrolyte balance is for water outside the cells to rush into the cells via osmosis. Although electrolytes are more concentrated inside the cells than outside, the water outside the cells is 'more concentrated' or 'less dilute' since it contains fewer electrolytes. Both electrolytes and water move across the cell membrane in an effort to balance concentration. From the cell's point of view, water intoxication produces the same effects as would result from drowning in fresh water. Electrolyte imbalance and tissue swelling can cause an irregular heartbeat, allow fluid to enter the lungs, and may cause fluttering eyelids. Swelling puts pressure on the brain and nerves, which can cause behaviours resembling alcohol intoxication. Swelling of brain tissues can cause seizures, coma and ultimately death unless water intake is restricted and a hypertonic saline (salt) solution is administered. Q. It's N o t H o w M u c h w e Drink, It's H o w Fast w e D r i n k It!
The kidneys of a healthy adult can process fifteen liters of water a day. We are unlikely to suffer from water intoxication, even if we drink a lot of water, as long as we drink over time as opposed to intaking an enormous volume at one time. As a general guideline, most adults need about three quarts of fluid each day. Much of that water comes from food, so 8-12 eight ounce glasses a day is a common recommended intake. We may need more water if the weather is very warm or very dry, if we are exercising, or if we are taking certain medications. -10 C H E M I S T R Y T O D A Y |FEBRUARY'06
163
Practice Paper for
¥
West Bengal J E E 2006 1. The compound which does not react with CH 3 COCI is (a) RNH 2 (b) R 2 NH (c) R 3 N (d) all of these. 2. Which of the following is the strongest acid? (a) CHjCOOH (b) HCOOH (c) ClCH 2 COOH (d) CI 2 CHCOOH. 3. Carboxylic acids do not give the characteristic reactions of C = O group because of (a) polar nature (b) resonance (c) symmetrical structure (d) attached alkyl group. 4. (a) (b) (c) (d)
A Idol contains - CHOH and COOH groups - CHO and - CH 2 OH groups - CHO and - CHO groups - CHOH and C = O groups.
5. A ketone that does not form a cyanohydrin is (a) C 2 H 5 COCH 3 (b) CH3COCH3 (c) C 6 H 5 COC 6 H 5 (d) CH 3 COC 6 H 5 . 6. (a) (c) (d)
Which is true about ionic bonds? directional nature (b) isomerism high melting and boiling points non crystalline nature.
7. Which is not true in case of an ionic bond? (a) it is a linear bond (b) no bond is 100% ionic (c) it is f o r m e d between two atoms with large electronegativity difference (d) its formation is favoured by low charge cation and anion. 8. The element with atomic number 20 will most likely combine chemically with the element whose atomic number is (a) 14 (b) 10 (c) 11 (d) 16.
9. (a) (b) (c) (d)
Exam on > 22nd a n d 23rd -LApril 2006,
pi bond increases bond length decreases bond length distorts the geometry of molecule makes homoatomic molecules more reactive.
10. The bond formed in fluorine molecule is due to (a) s-s overlapping (b) s-p overlapping (c) p-p overlapping (d) hybridisation of orbitals. 11. The mixture of ethanol and sulphuric acid is heated in a closed flask at 1 4 0 ° C . The flask would contain (a) H 2 S 0 4 and C 2 H 5 O C 2 H 5 only (b) H 2 0 , H 2 S 0 4 and C 2 H 5 H S 0 4 only (c) H 2 0 , C 2 H S H S 0 4 , C 2 H 5 O C 2 H 5 and H 2 S 0 4 only (d)
H 2 0 , C2HSOC2H5, C 2 H 5 H S 0 4 and
12. The (a) (c) (d)
(CH 3 ) 2 CHC1 + Nal acetone (CH 3 ) 2 CHI + NaCl above reaction is known as Perkin's reaction (b) Finkelstein reaction Stephan's reaction Sabatier and Senderson's reaction.
13. The reaction : CH 3 Br + OH"" (a) S N 1 (b) S n 2 (c) S E 1 (d) S e 2.
C2H5OH.
CH 3 OH + B r is
14. An alkyl halide reacts with metallic sodium in dry ether to form an alkane. The reaction is known as (a) Frankland's reaction (b) Sandmeyer's reaction (c) Wurtz reaction (d) Wurtz-Fitting reaction. 15. (a) (c) (d)
S N 1 displacement is rapid for 1-bromopentane (b) 2-bromopentane 2-bromo-2-methylbutane all have equal rates.
16. On passing steam over silicon, we get (a) SiO z + H 2 (b) S i 0 2 + H 2 0 (c) SiO, + N , (d) SiO. 17. Fluorine can be freed from HF by passing the mixture through
164 CHEMISTRY TODAY
JANUARY '06
(a) an alkaline solution (c) H 2 0
(b) conc. H 2 S0 4 (d) NaF.
18. Fluorine does not show variable oxidation state because of (a) its small atomic size (b) its high electronegativity (c) non-availability of (/-orbital (d) low dissociation energy of F - F bond. 19. the (a) (c)
When calcium fluoride is heated in a glass tube, vapours come out from glass tube are H 2 SiF 6 (b) Si0 2 HF (d) Na,SiF 6 .
20. Fluorine is a stronger oxidising agent than chlorine 'In aqueous solution. This is attributed to many factors except (a) heat of dissociation (b) electron affinity (c) ionisation potential . (d) heat of hydration. 21. (a) (b) (c)
When heat is evolved in a reaction, it is called an endothermic reaction an exothermic reaction a redox reaction (d) none of these.
22. (a) (b) (c) (d)
Heat of a reaction does not depend on temperature of the reaction the path by which final product is obtained physical states of the reactants and products whether the reaction is carried out at constant pressure or at constant volume.
23. The relationship between enthalpy change (AH) and internal energy change (AE) for a system is given by (a) AH = AE + PAV (b) AH = AE - PAV (c) AH = AE + PV (d) AH = AE + RT. 24. The heat of neutralisation of a weak acid is than that of a strong acid. (a) less than (b) more than (c) equal to (d) none of these. 25. The heat change in a chemical reaction at constant pressure is (a) AH (b) AE (c) AT (d) E. 26. A nuclear reaction must be balanced in terms of (a) mass (b) energy (c) number of electrons (d) mass and energy. -10 C H E M I S T R Y T O D A Y |FEBRUARY'06
27. the (a) (c)
If the quantity of a radioactive element is doubled, rate of disintegration is halved (b) is doubled slightly increases (d) remains unaffected.
28. (a) (b) (c) (d)
In the third period from left to right reducing property decreases reducing property increases oxidising property increases oxidising property remains same.
29. the (a) (c)
The first ionisation potential of Si, P and S are in order Si < P < S (b) Si > P > S Si < P > S (d) Si > P < S.
30. Which of the following is crystal lattice of aluminium? (a) body centered cubic (b) face centered cubic (c) hexagonal closely packed (d) none of these. 31. Electrode potential of standard hydrogen electrode is (a) zero (b) 2 V (c) 0 . 3 V (d) 1.6 V. 32. The time required in hours to decompose electrolytically (a) 9 (b) (c) 36 (d)
for a current of 3 ampere 18 g of H z O is 18 54.
33. IO-2 g atom of Ag can be oxidised to Ag+ in the electrolysis of AgN0 3 solution using silver electrode by (a) 965 coulomb (b) 96500 coulombs (c) 9650 coulombs (d) 96.5 coulombs. 34. (a) (b) (c) (d)
In a Galvanic cell, energy changes are chemical energy —» electrical energy electrical energy —> chemical energy chemical energy —» internal energy internal energy —> electrical energy.
35. Silver from silver nitrate is deposited by copper because (a)
£°(Cu2+.Cu, Y. 57. Of the following solvents, the one most likely to dissolve ionic compounds is (a) carbon tetrachloride (b) methanol (c) water (d) butyl ether. 58. (a) (b) (c) (d)
The maximum covalency is generally equal to the number of unpaired s-electrons the number of paired p-electrons the number of unpaired s- and ^-electrons the actual number o f s and /^-electrons in the valence shell.
59. pi bond is formed by (a) the overlapping of atomic orbitals on the axis of nuclei (b) by mutual sharing of p electrons (c) by sidewise overlapping of parallel oriented halffilled p-orbitals (d) overlapping of s-orbital with p-orbitals. 60. Noble gases do not react with other elements because they (a) are monoatomic (b) are not found in abundance (c) have very small size of their atoms (d) have completely paired up and stable electron shells. 61. When diethyl ether is treated with chlorine in dark, it forms (a) per chlorodiethyl ether (b) ethyl chloride (c) acetyl chloride (d) 1,1-dichloroether. 62. Hansdiecker reaction is the (a) reaction of alcohol with phosphorus tri-iodide (b) reaction of alkyl halide with sodium metal in the presence of dry ether (c) formation of alkyl bromide containing one carbon atom less from silver salt of carboxylic acids (d) reaction of alcohol with thionyl chloride. -10 C H E M I S T R Y T O D A Y |FEBRUARY'06
63. Among isomeric halides, the boiling point is more for (a) CH3(CH2)3C1 (b) (CH3)2CHCH2C1 (c) C(CH3)3C1 (d) none of these. 64. Formation of an alkane by the action of Zn on alkyl halide is called (a) Wurtz reaction (b) Kolbe's reaction (c) Ullman's reaction (d) Frankland's reaction. 65. Substitution of chlorine takes place at high temperature for (a) CH3 - CH = CH 2 (b) H 2 C = CH, (c) HC = CH (d) none of these. 66. Heat of neutralisation of a strong base with a strong acid is (a) - 1 3 . 7 kcals (b) +13.7 kcals (c) -12.7 kcals (d) none of these. 67. H2 + Cl2 -> 2HC1; AH = - 4 4 kcal mol"1. In this reaction heat of formation of HCl in kcal is (a) - 44.0 kcal mol"1 (b) +44.0 kcal mol' 1 1 (c) -22.0 kcal mol' (d) +22.0 kcal mol- 1 . 68. By convention the enthalpy of an element in its standard state is assumed to be (a) 1 kcal mol"1 (b) 100 kcal mol-' (c) 0 kcal mol-1 (d) 250 kcal m o K 69. Enthalpy of a reaction is given as (a) H = E + PV (b) H = E - PV (c) AH=AE + PAV (d) AH = AE - PAV. 70. (a) (b) (d)
In an endothermic reaction heat is converted into electricity heat is absorbed (c) heat is evolved heat is converted into mechanical work.
71. Quantity of electricity is measured in (a) ampere sec (b) ampere (c) ampere sec"1 (d) ampere -1 sec. 72. Time taken to deposit 100 g of aluminium from an electrolytic cell containing A1 2 0 3 at a current of 125 ampere is (a) 1.2 hr (b) 1.8 hr (c) 2.4 hr (d) 3.2 hr. 73. Passing a current through molten aluminium chloride for some time produced 11.2 litres of Cl2 at NTP at anode. The quantity of aluminium deposited at cathode is 13
(a) 29 g (c) 9 g
(b) 18 g (d) 4.5 g.
74. The current strength in amperes required to liberate 10 g of bromine from KBr solution in half an hour is (a) 6.7 (b) 7.6 (c) 5.7 (d) 4.7 75. (a) (b) (c) (d)
In a galvanic cell, a salt bridge is used to complete the circuit reduce electric resistance in the cell attain equilibrium carry salts for reaction occurring in cell.
76. Moderate electrical conductivity is shown by (a) silicon (b) graphite (c) diamond (d) carbon. 77. The purpose of addition of KF to HF in the preparation of F2 by electrolysis is (a) to decrease the conductivity of HF (b) to increase the conductivity of HF (c) to increase the concentration of F2 (d) none of these. 78. Fluorine reacts with strong NaOH to give (a) 0 2 (b) OF2 (c) H 2 (d) 0 3 . 79. Which is the strongest reducing agent? (a) HF (b) HCI (c) HBr (d) HI. 80. (a) (b) (c) (d)
Which of the following is a false statement? Halogens are strong oxidising agents. Halogens show only - 1 oxidation state. HF molecules form inter halogen molecular H-bonds. Fluorine is highly reactive.
81. Which of the following represents acid-base pair of the equilibrium given below? HCI + 2H 2 0 H , 0 + + Cl" + (a) HCI, H , 0 (b) HCI, Cl(c) C1-, H 2 0 (d) HCI, H 2 0. 82. The pH of a solution is 5.0. If its hydrogen ion concentration is decreased 100 times, the solution will be (a) more acidic (b) more basic (c) neutral (d) of the same acidic strength.
(a) pure water (c) basic solution
(b) neutral water (d) acidic solution.
84. pH of human blood is (a) 7.9 (b) 6.8 (c) 7.1 (d) none of these. 85. The standard electrode potentials of Ag, Cu and Zn are 0.8 V, 0.34 V and -0.76 V respectively. Which one of the following can be stored? (a) CuS0 4 in zinc vessel (b) AgN0 3 in copper vessel (c) Cu(N0 3 ) 2 in silver vessel (d) AgN0 3 in zinc vessel. 86. (a) (c) (d)
The activity of radioisotopes changes with temperature (b) pressure chemical environment none of these.
87. A wooden article and freshly cut down tree are 7.6 and 15.2 min"1 g~' of carbon ( t m = 5760 years) respectively. The age of the article is (a) 5760 years
(b) 5760 x
( 15 2 (c) 5760x1 - j - ^ | years
(d) none of these.
88. (a) (b) (c) (d)
fU 5—/ 2
years
As we move from Na to CI along third period metallic character increases non-metallic character decreases metallic character decreases metalloid character remains same.
89. (a) (b) (c)
Ionisation potential of P is higher than S because P is more electronegative than S the 3p orbital is more than that of S the 3p orbital is half filled in P while it is partially filled in S (d) none of these.
90. The structure of magnesium metal is (a) body centred cubic (b) face centred cubic (c) hexagonal (d) tetrahedral. 91. Which of the following particles is emitted in the nuclear reaction? 27 , 5 P 30 + 13A1 + 2He" (a) o ( b ) (c) ,H> (d) |H 3 .
83. A pH of 7 signifies 54
-10
C H E M I S T R Y T O D A Y|FEBRUARY'06 168
92. (a) (b) (c) (d)
Lighter elements such as Li, B, C, O etc. show artificial radioactivity only natural radioactivity artificial as well as natural radioactivity no radioactivity.
93. (a) (c) (d)
Tyndall effect in colloidal system is due to scattering of light (b) reflection of light absorption of light presence of electrically charged particles.
94. the (a) (c)
In adsorption to Freundlich adsorption isotherm, adsorption at low pressure is proportional to P (b) P-] m P (d) P" (where n = 0 to 1)
95. Which of the following is true about physical adsorption? (a) it is reversible (b) decreases with temperature (c) it is exothermic (d) all of these. 96. The solubility product of As2S3 is given by the expression (a) Ksp = [As 3+ ] [S2 ] (b) Kxp = [As3+]2 [S 2 1 3 3+ 2 1 (c) Ksp = [As ]' [S ] (d) Ksp = [As3+]3 [S2-]2. 97. Let solubilities of AgCl in H 2 0, 0.01 M CaCl 2 , 0.01 M NaCl and 0.05 M AgN0 3 be Su S2, S3 and SA respectively. What is the correct relationship between these quantities? (a) Si > S2 > S3 > S4 (b) > S2 = S 3 > S 4 (c) S, > S 3 > S2 > S 4 (d) S4 > S2 > S3 > Sj. 98. A solution which resists the change in its pH value on addition of some amount of an acid or a base is called
(a) isochoric solution (c) buffer solution 99. (a) (c) (d)
(b) amphoteric solution (d) neutral solution.
The value of Ksp can be negative (b) positive negative or positive is always a whole number.
100. Which of the following is a Lewis acid? (a) H 2 0 (b) SnCl 4 (c) C 2 H 5 OH (d) Cl". ANSWERS
1. 6. 11. 16. 21. 26. 31. 36. 41. 46. 51. 56. 61. 66. 71. 76. 81. 86. 91. 96.
(c) (c) (c) (a) (b) (d) (a) (d) (a) (c) (a) (a) (d) (a) (a) (b) (b) (d) (a)
(b)
2. 7. 12. 17. 22. 27. 32. 37. 42. 47. 52. 57. 62. 67. 72. 77. 82. 87. 92. 97.
(d) (a) (b) (d) (b) (b) (b) (c) (d) (c) (c) (c)
(c) (c) (c) (b) (b) (a) (a) (c)
3. 8. 13. 18. . 23. 28. 33. 38. 43. 48. 53. 58. 63. 68. 73. 78. 83. 88. 93. 98.
(b) (d) (b) (c) (a) (b) (a) (c) (b) (b) (a) (d) (a) (c) (c) (a) (b)
(c) (a) (c)
4. 9. 14. 19. 24. 29. 34. 39. 44. 49. 54. 59. 64. 69. 74. 79. 84. 89. 94. 99.
(d) (b) (c) (a) (a) (c) (a) (d) (a) (a) (a) (c) (d) (a) (a) (d) (d) (c) (a) (b)
5. (c) 10. (c) 15. (c) 20. (C) 25. (a) 30. (b) 35. (a) 40. (b) 45. (a) 50. (a) 55. (c) 60. (d) 65. (a) 70. (b) 75. (a) 80. (b) 85. (c) 90. (c) 95. (d) 100. (b)
E S S Complete Book for
WB JEE'06
C H E M I S T R Y T O D A Y | JANUARY '06
13
The nanoscience of MMHNMMI
A
KAJAL
sk the millions of women who routinely ring their eyes with kajal about nanotechnology, and chances are you would receive a vacant stare in return. For eons now, Indian women have adorned their eyes with the sooty cosmetic little knowing that one day it would excite the world of molecular science with its simplicity. Just the other day, the Indian Institute of Technology, Kanpur, announced that kajal constituted carbon nanotubes (CNT). So? Now consider this : till now the generation of CNT was an expensive affair in which an organic compound like benzene was vapourised and CNT extracted from the deposition of the smoke. The equipment used in the process alone costs over Rs. 10 lakh. And how much does it costs to burn oil in an ordinary lamp and catch the soot on a plate - the way kajal is made at homes all over India? Nano derives from the Greek nanos, or a dwarf. In actual measurement, a nanometre is a billionth of a metre, nanotechnology, therefore, dealing with particles smaller than in microtechnology. Nanotech, in its basic sense, is using molecular building blocks in an array of applications, from medicine and manufacturing to biotech and optics. Unique among elements, carbon can bond to form sheets that can be rolled into tubular fibres, known to be among the strongest fibres known, 10 to 100 times stronger than steel by weight. Sabyasachi Sarkar, a chemistry professor at IIT-K, was working on the production of fullerenes, another ballshaped, sub-micro structure, in 1992, when he detected that waste insoluble carbon soot seemed to have a substantial amount of CNT. Based on this finding, Sarkar tried to produce CNT from the traditional oil-burning lamp in which pure carbon, or kajal is produced. After his initial studies on generation of CNT, Sarkar was awarded a Rs. 32 lakh project by the Indian Government's Department of Science and Technology (DST) in September 1994. He said his focus, as of scientists elsewhere, was on developing a cost-effective method to generate CNT and finding a way to make CNT water soluble for medical use.
10
RSW^BMMI
He chuckles about how blind we have been over the years. Even the Ramayana and Mahabharata mentioned the kajal. "Traditionally, the grandmother applies fresh kajal to the six-day-old baby to prevent eye-ailments", he added. No one knew this pure carbon could be a source of much-needed carbon nanotubes. As for the other eyeliner, the surma, Sarkar says it is not pure carbon like kajal but emanates from lead sulphide and is of Arabic origin. Sarkar was able to extract up to 40 percent of the kajal as CNT. More important, Sarkar not only produced cheap CNT through a traditional method but also managed to make it water soluble. He did this by treating CNT with nitric acid, which incorporated some hydrophilic groups and thus made it soluble. CNT has multifarious uses. "The dry-state uses include manufacturing of picture tube for display devices, which would be much cheaper and less power consuming", says Sarkar. He also envisages CNT replacing optic fibres used in telecommunication since it minimises distortion of sound and disturbances in the line. Other uses of CNT are in manufacturing of reusable packaging material and in electronics. Wet-use CNT can be applied in drug delivery. Sarkar said, for instance, that if drug for cancer in a specific body part was to be delivered without affecting the other parts, the magnetic property of CNT was extremely helpful. "The drug is placed in a CNT and injected into the blood. It is then dragged to the affected part with magnetic material and then blasted using electro-magnetic radiation," he explained. Despite the obvious fallout of his discovery, Sarkar has not patented the process. "I do science, not business," he said. He suggests the production of kajal should be promoted as a cottage industry that would generate employment for thousands of educated, unemployed people. Courtesy : I n d i a n E x p r e s s CHEMISTRY TODAY | JANUARY '06
AIIMS
( C B S E ) ( D P M T ) ( A F M C ~ ] ( V M M C ) (EAMCET) (WB-JEE) ( B H U
) ( CMC )
2006 Medical Entrance Exam ( UP
CPMTJ
(CET Karnataka]
Practice Test Paper
( M a n i p a l PMT) (
JIPMER
(MP PMT] ( M G I M S ) (PMDT B i h a r ) (PMT H a r y a n a ) ( K e r a l a P M T ) ( R a j . P M T )
TNPCEE )
1. Which of the following is slag? (a) Si0 2 (b) CaSi0 3 (c) CaO (d) Ca(0H) 2 .
10. The energy of the electron of the H-atom orbiting in a stationary orbit of radius rn is proportional to (a) r„ (b) r2 (c) 1 !rn (d) 1 !rn\
2. Which one of the following is an important ore of copper? (a) malachite (b) calamine (c) galena (d) dolomite.
11. Cyanide process is used to obtain (a) Cu (b) Ag (c) Zn
3. Which one of the following metals corrodes readily in moist air? (a) gold (b) silver (c) nickel (d) iron. 4. In the extraction of Fe from haematite ore, CaC0 3 acts as (a) flux (b) slag (c) lining material (d) none of these. 5. The froth floatation process is used for the concentration of (a) oxide ores (b) sulphide ores (c) minerals (d) slag. 6. An oxide of nitrogen has a molecular weight 30. The total number of electrons in one molecule of the compound (at. no. N = 7, O = 8) is (a) 14 (b) 15 (c) 7 (d) 16. 7. If n = 3, / = 0, m (for outermost shell) = 0 then the probable atomic number may be (a) 10, 11 (b) 11, 12 (c) 12, 13 (d) 13, 14. 8. I. III. (a) (c)
Pick out the isoelectronic species from the following. CH3+ II. H 3 O + NH, IV. C H 3 \ (b) III and IV I and II (d) II, III and IV. I and III
9. the (a) (c) (d)
In which of the following one electron system is radius of the first Bohr orbit minimum? hydrogen-atom (H) (b) deuterium ion (D+) singly ionized helium (He + ) doubly ionized lithium (Li 2+ ).
CHEMISTRY TODAY | JANUARY '06
(d) Ni.
12. Which of the following is ferrous alloy? (a) invar (b) solder (c) magnalium (d) type-metal. 13. Correct formula of potassium ferricyanide is (a) K 4 [Fe(CN)] 6 (b) K 3 [Fe(CN) 6 ] (c) KFe(CN) s (d) K 2 Fe(CN) 4 . 14. Sea-weed is important source of (a) iron (b) chlorine (c) iodine (d) bromine. 15. The acid employed for etching glass is (a) H 2 S0 4 (b) HC10 3 (c) HF (d) aqua regia. 16. the (a) (b) (c) (d)
The size of the species given below increases in order of Mg 2 + < N a + < F" < Al 3+ F" < AI3+ < Na + < Mg 2+ Al3+ < Mg2+ < Na + < F Na + < Al3+ < F" < Mg2+.
17. Which of the following has largest radius? (a) Mg2+ (b) Na + (c) 0 2 ~ (d) F". 18. Which of the following represents the electronic configuration of J-block elements? (a) (« - 1 )s2 d> ' 10 (b) (k - 1 )d]-10 ns2 l 10 2 4 (c) (n - l)d ns np (d) (n - ])p4 ns2. 19. If the speed of the electron in the first Bohr orbit of the hydrogen atom be x, then the speed of the electron in the third Bohr orbit is (a) x/9 (b) x/3 (c) 3x (d) 9x.
13
20. The ratio of energy of a photon with 2000 A wavelength to that of a photon with 4000 A wavelength is | (a) 1 : 2 (b) 1 : 4 (c) 2 : 1 (d) 4 : 1. 21. Cl2 gas is dried over (a) CaO (b) NaOH (c) K.OH (d) conc. H,S0 4 . 22. Iodine deficiency in diet causes (a) beri-beri (b) goitre (c) rickets (d) night blindness. 23. There is no S - S bond in (a) S 2 0 3 2 (b) S 2 0 4 2 " 2 (c) S 2 O s " (d) S 2 0 7 2 ". 24. Oxalic acid when heated with conc. H 2 S0 4 gives out (a) H 2 0 and C 0 2 (b) CO and C 0 2 (c) oxalic sulphate (d) C0 2 and HgS.
33. for (a) (cj
The starting material in the Birkland Eyde process manufacture of nitric acid is ammonia (b) N 0 2 gas air (a) cmli saltpetre.
| 34. The molecular formula of phosphorus is j (a) P (b) P 2 (c) P5 (d) P4. 35. The basicity of H 3 P0 4 is (a) 2 (b) 3 (c) 4
(d) 5.
36. Which of the following contains both ionic and covalent bonds? (a) CC14 (b) CaCl 2 (c) NH4C1 (d) H 2 0. 37. The shortest length of H-bond is present in (a) HF (b) H 2 0 (c) NH 3 (d) C 2 H 5 OH. 38. Which of the following does not exhibit resonance? (a)
C6HSOH
(c) N 2 0
(b)
C2H5OH
(d) S0 2 .
25. A solution of S 0 2 in water reacts with H 2 S precipitating sulphur. Here S0 2 acts as (a) an oxidising agent (b) a reducing agent (c) an acid (d) a catalyst.
39. The number of mole of atoms present in 10 g of calcium is (a) 0.1 mole (b) 0.2 mole (c) 0.25 mole (d) 0.4 mole.
26. The first ionization energies are in the order of (a) Na < Mg > AI < Si (b) Na > Mg > AI > Si (c) Na < Mg < AI < Si (d) Na > Mg > AI < Si.
40. 280 (a) (c)
27. When the first ionization energies are plotted against atomic numbers, the peaks are occupied by (a) alkali metals (b) halogens (c) noble gases (d) transition elements. 28. Which of the following has the biggest ionic radius? (a) O 2 " (b) Na + (c) K+ (d) Cl". 29. An element A (Z = 13) and another element B (Z = 8) combine together to form a compound. The formula of the compound is (a) AB (b) A2B (C) AB2 (d) A2B3. 30. The highest covalent character is found in (a) CaF2 (b) CaCl 2 (c) CaBr 2 (d) Cal 2 . 31. Which one of the folllowing molecules contains a lone pair of electrons on the central atom? (a) Cl2 (b) CH 4 (C) CHCI3 (d) NH 3 . 32. Which of the following oxides of nitrogen is the anhydride of HN0 3 ? (a) NO 58
(b) N 2 0 3
(C) N 2 0 4
(d) N 2 O s .
The number of molecules of oxygen present in ml of oxygen at STP is 7.53 x 1021 (b) 7.50 x io 21 23 6.02 x 10 (d) 7.53 x 1022.
41. The number of mole of C0 2 left after removing 1021 molecules from 200 mg of C 0 2 will be (a) 2 x 10 3 (b) 3 x IO"4 3 (c) 3 x IO" (d) IO 3 . 42. The number of milli moles contained in 1.6 g of NaOH is (a) 0.04 (b) 0.4 (c) 4 (d) 40. 43. If 1.12 litres of methane contains 3 x 1022 molecules at STP, the number of molecules in 5.56 litres of oxygen at STP, will be (a) 6 x 1022 (b) 1.5 x 1022 22 (c) 0.15 x 10 (d) 3 x 1022. 44. A gaseous mixture contains oxygen and nitrogen in the ratio of 1 : 4 by weight. The ratio of number of molecules is (a) 1 : 4 (b) 2 : 7 (c) 7 : 32 (d) 3 : 16. 45. The number of atoms in 0.004 g magnesium will be close to -10
C H E M I S T R Y T O D A Y |FEBRUARY'06 172
(a) 24 (c) 1020
(b) 96 (d) 6.02 x 1020.
46. Which of the following is not a characteristic of entropy? (a) it is a state function (b) it is a macroscopic property (c) it is extensive property (d) it is intensive property. 47. Which of the following is insoluble in dilute HCl? (a) aniline (b) triphenylamine (c) ethylamine (d) dimethylamine. 48. Aniline is basic because of the presence of (a) - N H 2 (b) - N H (c) - CN (d) - C O N H 2 . 49. The compound formed when aniline is gently heated with chloroform and potassium hydroxide solution is (a) benzonitrile (b) phenyl isocyanide (c) phenol (d) ammonia. 50. Which of the following may be prepared by Gabrielphthalimide synthesis? (a) aliphatic amines (b) aromatic amines (c) aliphatic amides (d) aromatic amides. 51. Schiff's bases are formed when aniline is condensed with (a) phenols (b) aryl chlorides (c) aromatic aldehydes (d) aliphatic alcohols. 52. Nitrobenzene on reduction with Zn-dust and aqueous NH4C1 produces (a) aniline (b) phenyl hydroxylamine (c) nitrosobenzene (d) none of these. 53. and (a) (c)
When nitrobenzene is heated with fuming HN0 3 concentrated H 2 S0 4 for several hours, it gives dinitrobenzene (b) trinitrobenzene DDT (d) none of these.
54. At 60°C a mixture of concentrated H N 0 3 and concentrated H 2 S0 4 converts benzene into (a) nitrobenzene (b) /w-dinitrobenzene (c) benzene sulphonic acid (d) 1,3,5-trinitrobenzene. 55. When nitrobenzene is reduced with Sn and concentrated HCl, the product is (a) C 6 H 5 NH 2 (b) C6H5NHC1 (c) C 6 H 5 OH (d) C 6 H 5 COOH. C H E M I S T R Y T O D A Y | JANUARY '06
56. The weight of iron which will be converted into its oxide by the action of 18 g of steam on it will be (Fe = 56, O = 16) (a) 20 g (b) 40 g (c) 45 g (d) 42 g. 57. The weight of 50% solution of HCl required to react with 100 g of CaC0 3 would be (a) 73 g (b) 100 g (c) 146 g (d) 200 g. 58. What will be the weight of oxygen that is required for the complete combustion of 2.8 g of ethylene? (a) 2.8 kg (b) 6.4 kg (c) 96 kg (d) 9.6 kg. 59. The weight of carbon required to reduce 165 g of C0 2 to CO will be (a) 40 g (b) 43 g (c) 45 g (d) 48 g. 60. The minimum amount of hydrogen required to reduce completely 7.95 g of CuO (mol. wt. 79.5) will be (a) 0.5 g (b) 1 g (c) 2240 ml at STP (d) none of these. 61. The volume of S0 2 at STP formed when 1260 g of sodium sulphite react with sufficient sulphuric acid is (a) 112 litres (b) 224 litres (c) 22.4 litres (d) 11.2 litres. 62. The weight of ammonium chloride required to prepare 22.4 litres of ammonia at STP is (a) 53.5 g (b) 107 g (c) 26.75 g (d) 40 g. 63. 18 g of water is electrolysed. Volume of oxygen obtained at STP is (a) 22.4 litres (b) 11.2 litres (c) 5.6 litres (d) 2.8 litres. 64. 15 litres of hydrogen combine with excess of nitrogen to produce ammonia. The volume of ammonia in litres formed is (a) 5 litres (b) 8 litres (c) 10 litres (d) 12 litres. 65. 15 ml of a gaseous hydrocarbon required 45 ml of oxygen for complete combustion and 30 ml of C 0 2 were formed. The formula of the hydrocarbon is (a) C 3 H 6 (b) C 2 H 6 (C) C 2 H 2 (d) C 2 H 4 . 66. Among the following, the most basic compound is (a) benzylamine (b) aniline (c) acetanilide (d) /?-nitroaniline. 67. Toluene reacts with Cl2 in the presence of sun light to give
13
(a) benzyl chloride (c) p-chlorotoluene
(b) benzoyl chloride (d) o-chlorotoluene.
273 °C and 1 atm pressure is (a) 8.9 (b) 11.2 (c) 1
(d) 2.
68. Which of the following does not undergo FriedelCraft's reaction? (a) aniline (b) phenol (c) nitrobenzene (d) all of these.
79. and and (a)
69. Which of the following is not used as a reagent in Friedel-Craft's reaction? (a) alcohol (b) alkene (c) chlorobenzene (d) alkyl-halide.
80. A vessel contains 1 mole of 0 2 at 27°C and 1 atm. A certain amount of the gas was withdrawn and the vessel was heated to 327°C to maintain the pressure at 1 atm. The amount of gas removed was (a) 8 g (b) 0.2 mole (c) 0.25 mole (d) 0.5 mole.
70. Toluene on oxidation with alkaline KMn0 4 gives (a) benzaldehyde (b) potassium benzoate (c) benzoic acid (d) benzo quinone. 71. The reaction of toluene with chlorine in the presence of ferric chloride gives predominantly (a) benzoyl chloride (b) m-chloro toluene (c) benzyl chloride (d) o- and p-chlorotoluene. 72. Toluene is oxidised to benzaldehyde with chromyl chloride. The reaction is known as (a) Oppenauer reaction (b) Etard reaction (c) Wurtz-Fittig reaction (d) Rosenmund reaction. 73. Which xylene is most readily nitrated? (a) o-xylene (b) p-xylene (c) m-xylene (d) all at the same rate. 74. Which of the following shows maximum molar conductivity? (a)
[CO(NH,)6]C13
(b)
[CO(NH3)5C1]C12
(c)
[CO(NH3)4CI2]CI
(d)
[CO(NH3)3C13],
75. Which of the following deactivates benzene substitution? (a) - NHR (b) - OH (c) - COOR (d) - OR. 76. 20 ml of gas was collected at STR The pressure was then doubled and the temperature gradually changed until the volume of the gas became 20 ml again. The temperature at which this happened was (a) 173 K (b) 273 K (c) 373 K (d) 546 K. 77. A certain mass of H2 at 273°C and 3 atm pressure occupies 2 litres. What will be the volume of the gas at STP? (a) 2/3 litres (b) 1 litre (c) 2 litres (d) 3 litres. 78. The density of a gas (mol. wt. 44.8) in gm/litre at 10
The density of a certain mass of a dry gas at 27°C 760 mm pressure is 2.5 gm/litre. Its density at 7°C 740 mm pressure will be (in gm/litre) 0.9 (b) 1 (c) 1.2 (d) 2.3
81. Which produces ammonia on reaction with caustic soda? (a) ethyl amine (b) dimethyl amine (c) acetamide (d) aniline. 82. The isomer of an oxime is (a) R N 0 2 (b) R - O - C = (c) R - O - N = O (d) R - CONH 2 .
N
83. Which of the following is most reactive towards nucleophilic substitution reaction? (a) RC1 (b) ( R C 0 ) 2 0 (c) RCOC1 (d) RCONH 2 . 84. The most suitable reagent for laboratory preparation of acetyl chloride from acetic acid is (a) PC15 (b) HCI (c) SOC1, (d) PC13. 85. Which ofthe following has the highest melting point? (a) (CH 3 C0) 2 0 (b) CH 3 CN (c) CH 3 CONH 2 (d) CH 3 COCl. 86. Which of the following is not a /w-directing group? (a) - S0 3 H (b) - N 0 2 (c) - CN (d) - NH 2 . 87. Among the following the compound that can be most readily sulphonated is (a) benzene (b) nitrobenzene (c) toluene (d) chlorobenzene. 88. (a) (b) (c)
Gammexane is DDT benzenhexachloride (BHC) chloral (d) hexachlorobenzene.
89. Benzene reacts with CC14 in the presence of anhydrous A1CI3 to give (a) tetraphenylmethane (b) chlorobenzene CHEMISTRY TODAY | JANUARY '06
(c) tetrachlorobenzene (d) triphenyl methylchloride. 90. to (a) (b) (c) (d)
Anhydrous A1C13 in Friedel-Craft's reacton is used generate an electrophile generate a nucleophile generate a free radical absorb water.
91. When a solution of a primary aliphatic amine is treated with N a N 0 2 and HCl the effervesescence occurs due to formation of (a) CO, (b) N 0 2 (c) N 2 (d) H,. 92. The carbylamine reaction is associated with the name of (a) Wurtz (b) Kolbe (c) Hinsberg (d) Hoffmann. 93. (a) (b) (c) (d)
Hinsberg reagent is benzene sulphonic acid benzene sulphonyl chloride /7-toluene sulphonyl chloride none of these.
94. When an organic compound was treated with sodium nitrite and HCl in the ice-cold, nitrogen gas was evolved. The compound is (a) a nitro compound (b) a primary amine (c) a secondary amine (d) a tertiary amine. 95. An aromatic amine (A) was treated with alcoholic potash and another compound (F) when a foul-smelling gas was formed with formula C 6 H 5 NC, (7) was formed by reacting a compound (Z) with Cl, in presence of slaked lime. The compound (Z) is (a) C 6 H 5 NH 2 (b) CH 3 OH (c) CH3COCH3 (d) CHCI3.
99. In the presence of bright sunlight benzene reacts with chlorine to form (a) chlorobenzene (b) benzyl chloride (c) hexachloro-benzene (d) benzene hexachloride. 100. The main source of aromatic compound is (a) wood (b) coal tar (c) coal gas (d) petroleum. ANSWERS
1. (b) : The undesired impurities present in ores are called gangue or matrix. To remove gangue, certain substances are mixed with concentrated ore which combine with gangue to form fusible material which is not soluble in molten metal. The substances used are called fluxes and the fusible material formed during reduction process is called slag. Si0 2 + CaO - » CaSiOj flux
2.
(a):
gangue
Malachite Calamine Galena Dolomite
slag
-
CuC0 3 • Cu(OH) 2 ZnC0 3 PbS CaCO, • MgC0 3
3. (d) : Corrosion is d e f i n e d as the gradual transformation of a metal into its combined state because of the reaction with the environment. When iron is exposed to moist air, it is found covered with a reddish brown coating which can easily be detached. The reddish brown coating is called rust. 4. (a) : CaCO, decomposes into CaO and CO,. CaO acts as a flux as it combines with silica present as an impurity to form a fusible slag. CaC0 3 CaO + CO, CaO + Si0 2 -> CaSi0 3 5.
(b)
6.
(b) : Molecular formula weight of the compound = 30
96. Benzene is converted into toluene by (a) Wurtz reaction (b) Etard's reaction (c) Fittig reaction (d) Friedel-Craft's reaction.
The oxide would thus be NO = (14 + 16) = 30 At. number of N and O being 7 and 8, the total number of electrons present = (7 + 8) = 15.
97. In Friedel-Craft's reaction, the catalyst used is (a) Raney Ni (b) Mg and ether (c) anhydrous A1C13 (d) Na and liquid NH 3 .
7. (b) : Electronic configuration of the element may be Is 2 2s2 2pb 3s1 or Is 2 2s22pb 3s 2 . Hence, its atomic number will be 11, 12.
98. (a) (c) (d)
Benzene undergoes predominant reactions by electrophilic addition (b) nucleophilic addition electrophilic substitution nucleophilic substitution.
-10 CHEMISTRY TODAY |FEBRUARY'06
8.
(d) : The number of electrons in I are (6 + 3 - 1) = 8 II are (3 + 8 - 1) = 10 III are (7 + 3) = 10 IV are (6 + 3 + 1) = 10. 175
9. (d) : As we know that r„ « 2 /Z For the same value of principal quantum number the radius decreases as the atomic number Z increases. For, H, Z = 1; D+, Z = I; He+, Z = 2 ; Li2+, Z= 3 The radius of first Bohr orbit is the smallest one for Li2+. 1 2 10. (c) : Kinetic energy of the electron = — wv Ze1
and potential energy of the electron = Total energy (E) of the electron = K.E.
47t£0r +
P.E. 1
1 2 Ze —mv 4 ne0r 2 Centripetal force = (coulombic atractive force between electron and proton) mv r E=
Ze2
mv2 =
47te0/-' z
Ze [8ne0r
Ze
47tE0r
Ze 8itE0r 2
Ze 8ne0r
the radius. The oxide ion has only 8 protons, the ratio is the smallest one. Hence 0 2 ~ has largest radius. 18. ( b ) : In cf-block elements the electrons occupy the c/-subshell and the last two principal shells are incomplete. Again, after filling the ns orbital the electron enters the {n-\)d orbital. T 19. (b) : We know that, velocity = no. of Bohr orbit Therefore, the velocity of the electron in the third Bohr orbit = x/3. , he 20. (c) : As we know, £ = «o = — K £, _ X2 _ 4000 _ 2 1 E x — . Therefore, c - , ~ , X ' E2 2000 1 21. (d) : As others (1), (2) and (3) reacts with Cl2. 22. (b) 23. (d) : The structure of S 2 0 7 2 " is
That is E Na2Ag(CN)2 + 4NaOH
•• :o:
s^.. :o:
Therefore, it has no S - S bond. Rest of them have S - S bond in their structures.
soluble complex
12. ( a ) : Invar is an iron alloy containing 36% Ni. 13. (b) 14. (c) : Laminaria species contain 0.5% of iodine in their ashes (known as kelp) in the form of iodides. 15. (c) : Glass being a mixture of sodium and calcium silicates reacts with hydrofluoric acid forming sodium and calcium fluorosilicates respectively. Na 2 Si0 3 + 3H2F2 Na2SiF6 + 3H 2 0 CaSi0 3 + 3H2F2 -> CaSiF6 + 3H 2 0 16. (c)
Species Z e Z/e 10 12/10 = 1.2 Mg 2+ 12 10 Na + 11 11/10 = 1.1 9/10 = 0.9 F9 10 3+ Al 13 10 13/10 = 1.3 We know the bigger the value Z/e, the smaller is the ionic radius. Hence increasing order of radius AI3+ < Mg 2+ < Na + < F". 17. (c) : All these species are isoelectronic. Again the larger value of proton/electron the smaller is
50
24. (b) : H,C 2 0 4
cone. H 2, S O 4. dehydration of H 2 0
25. ( a ) : S0 2 + 2H2S
.
.
COT + CO,T
2H 2 0 + 3S
Here oxidation number of S reduces from +4 to 0. But it oxidises H2S (-2 to 0) So, S0 2 in this reaction acts as oxidising agent. 26. (a) : All these elements belong to period 3 in the periodic table. The first ionization energy increases in a period, with the exception that ionisation energy of group IIIA is less than that of group IIA element. Hence, the order of increasing ionisation energy is Na < Mg > Al < Ai. 27. (c) : As we know that the noble gases have the highest value of first ionisation energy in their period, hence noble gases occupy the highest points in the curve. 28. (d) : Isoelectronic cations have smaller radius than anions and the radius increases in a group. 29. (d) : Electronic configuration of A (Z = 13), 2, 8, 3 Electronic configuration of B (Z = 8), 2, 6 CHEMISTRY TODAY | JANUARY '06
A by losing 3 electrons and B by gaining two electrons achieve the noble gas configuration. Hence, valency of A is +3 and that of B is - 2 . Therefore, the formula of the compound is A2B3. 30. (d) : The cation in all the compounds is the same Ca2+. The anion is halide ion, The size of the iodide ion is greatest of all other halide ions. By Fajan's rule, the maximum covalent character of these exists in Cal 2 . 31. (d) 32. (d) : 2 H N 0 3
~H2°>
N205
33. (c): For the manufacture ofHN0 3 , reactions taking place in air are as follows: N2 + 0 2 ^ 2NO - 43,200 calories 2NO + 0 2 -> 2NO, 2N0 2 + H 2 0 HNO3 + HN0 2 3HN0 2 HN0 3 + 2NO + H 2 0 34. ( d ) : As the molecular formula of phosphorus is P 4 . 35. (b): As in orthophosphoric acid (H 3 P0 4 ), number of ionisable hydrogen atoms (basicity) is three. 36. (c) : The Lewis structures of these compounds are :Cl:
..
I
ci: ,[ca 2+ ] [:ci:]_ I :ci: oo (b)
:CI
- C -
••
H
I
H - N - H
M L
H
J
•
H
AH
M W) (a) and (d) have only covalent bonds (b) contains an ionic bond (c) contains both covalent and ionic bonds. 37. (a) : Considering the size of the F, N, O the atom of the smallest radius of the three is fluorine and fluorine is the most electronegative atom. The H-bond in HF is, therefore, shortest in length. 38. ( b ) : The species exhibiting resonance requires the presence of a rc-bond or the lone pair suitably placed in the structure of molecule or ion. The structures are
CH 3 : CH 2 : O : H :N=N^O
0 = S—O
-10 C H E M I S T R Y T O D A Y |FEBRUARY'06
UjpJ
» CH3-CH,-0-H,
® ..'— .. © : N = N = 0 : , : 0 = S — O: The condition is not present in ethanol (C2H5OH). 39. (c) : This atomic weight of calcium = 40 .". 40 g of Ca make 1 mole 10 g of Ca make — x 10 = 0.25 mole. 40 40. (a) : Since, one mole of oxygen = 32 g = 6.02 x io 23 molecules of 0 2 = 22400 ml 0 2 at STP Number of molecules of oxygen in 280 ml of 0 2 at 280 STP = x 6.02 x 1023 molecules 22400 = 7.53 x io21 molecules. 41. (c) : v 6.02 x io 23 molecules of C0 2 = 1 mole of C0 2 10,21
1021 molecules of CO, =
6.02 xlO 23 200 1 Now, 200 mg of C0 2 = — : * — mole 10
= —xlO 22
_9
10,-2 6.02
mole
mole 1 xlO" 22 6.02, 3 = 3 x 10" mole.
Number of mole of CO, left = 42. (a) : Millimoles of NaOH Mg of NaOH formula wt. of NaOH in mg _ *600 _ 0 mj|jj mole 40,000
10
1600 40x 1000
43. ( b ) : As, vol. of methane at STP _ No. of molecules of CH 4 vol. of oxygen at STP No. of molecules of O, 1.12 3x10 22 0.56 no. of molecules of 0 2 => No. of molecules of O, =
3xl() 22 x0.56 1.12
1.5 x io 22 . No. of molecules of 0 2 44. (c) : As, No. of molecules of N 2 _ moles of 0 2 ^ Avogadro's number moles of N 2 Avogadro's number 13
wt. of O, mol. wt. of O, wt. of N , mol. wt. o f N 2
1/32 4/28
1 32
28 4
168x18 „„ 18 g of steam will react with — — — = 42 g.
7 32
57. (c) : CaCO, + 2HCI 100 g
Amount of HCI required for 100 g of CaC0 3 = 73 g v 50 g of HCI are contained in 100 g of 50% acid 100x73 1/1/f .-. The wt. of 50% acid = — — — = 146 g .
45. (c) : Since, 24 g of magnesium contains 6.02 x 10" atoms 6.02 x l 0 2 3 x 0.004 ; 24 20 = IO (nearly).
0.004 g of Mg contains = 46. (d)
47.
(b)
49. (b) : [ O J
48.
58. (d) : C 2 H 4 + 3 0 , 2 8 kg
(a)
>
^ 59. (c) : CO, + C
N=C + 3KC1 + 3H 2 0 This reaction is called isocyanide reaction and is used as a qualitative test for primary amines. 50. (a)
51. (c): Aniline reacts with benzaldehyde in 1 : 1 molar ratio to produce benzalaniline. (also called Schiff's base or anil) A C 6 H 5 NH 2 + O = CH - C 6 H 5 » C6H,N = CH - H,0 Benzaldehyde
NO,
C6H5 Z n / N H . C I (aq)
C6H5NHOH
44 g
NO,
NO, fuming HNO,
[ O J
high temp.
NO:2
0
NO,
v
1,3,5-trinitrobenzene
54. (a)
+ conc. HNO,
2—
50-55°C
benzene
2CO
79.5 g
2 g
79.5 CuO is reduced by 2 g of hydrogen .-. 7.95 g CuO is reduced by 0.2 g of H2 Again, 2 g of hydrogen is equivalent to 22400 ml of H, at STP. 0.2 g of H2 is equivalent to 2240 ml H, at STP. 61. (b) : Na 2 S0 3 + H,S0 4 (46 + 32 + 4 8 )
NO,
= 126 g
nitrobenzene
3Fe
(3 x 5 6 ) g
+
(4 x 18)
22.4 lit at STP
wt. of unknown
22.4 litres mol. wt. 22.4 _ A=> x = 53.5 g. 22.4 ~ 53.5
18 g
aniline
4H,0
Fe 3 0 4 + 4H, g
Since, 72 g of steam reacts with 168 g of Fe 64
given volume
63. (b) : H 2 0 - electrolysed
(ii) N a O H
56. (d) :
Again,
NH,
(i) Sn/conc. HCI
Na,S0 4 + H , 0 + S0 2 2 2 . 4 litres at S T P
. . given wt. vol. of unknown Again, - — : — = _ (per mole) mol. wt. 22.4 litres 1260 x 1260x22.4 lit. 126 22.4 lit. 126 = 224 litres. 62. (a) : NH4C1 NH, + HCI
nitrobenzene
55. ( a ) :
= 9.6 kg.
12 g
(14 + 4 + 3 5 . 5 ) g
NO,
conc. H,SO / 1
28
44 g of CO, are reduced by 12 g of carbon 12 .-. 165 g of CO, are reduced by — x 165 g of carbon 44 = 45 g. 60. (c) : CuO + H2 Cu + H 2 0
phenyl hydroxyl amine
53. (b) :
2C0 2 + 2 H , 0
9 6 kg
Y 28 kg of ethylene are completely burnt by 96 kg of 0 2 2.8 kg of ethylene are completely burnt by
+ CHC1, + 3K.OH
52. (b) :
CaCI, + CO, + H , 0
73 g
64.
(c) :
15 3H2 + N 2 3
-O, (11.2 litres o f O , at S T P )
* 2NH 3 2 CHEMISTRY TODA\
JANUARY '06
given volume _ unknown volume no. of molecules no. of molecules 15 x A- = 10 litres. j 2 65. (d) : Combustion reaction of hydrocarbon C r H v C , H
V
+ [ X + ^ I O
= * C O
v o ''
1 vol
15 ml
2
15| -T + - J
ml
2
, y i2
+ | H
As we know from the gas equation. 5H r. P.V.T, 3 x 2 x 2 7 3 lr V-, = 1 1 2 = = 3 litres. 546x1 TXP2
I5x ml
78. (c) : As we know that, density, P = x = 2.
Again, 15lx + ^-J = 45 (volume of 0 2 reacted) ^- = 3 - j c = 3 - 2 = 1 jc + —= 3 4 4 =f y = 4. ;. Formula of hydrocarbon = CVH;. = C 2 H 4 . =>
66. (a)
benzyl chloride
68. (d) : The reaction of an alkyl halide or acyl halide with benzene in the presence of a Lewis acid, generally A1C13, is known as Friedel Craft's reaction. 69. (c) 70. (b) : - CH 3 group is oxidised to - COOH group. CH3
71. ( d ) :
CH3
CH3
Cl,
[ O j
FeCl 3
o-chlorotoluene
72. (b) :
CI p-chlorotoluene CHO
CH, C S 2 (25-45°C) (toluene)
IWi P~>
PM RT
Here, we are given P = 1 atm, R = 0.082 litre atm K"1 moL 1 M = 44.8 gm/mole, T=(273 + 273) K = 546 K 1 44.8 = 1 gm/litre. .'. P = x 0.082 546 79. (d) : As we know,
= P{l] P2T2 Here we are given p, = 2.5 g/litre, p, = ? 7, = (273 + 27) K = 300 K T2 = (273 + 7) K = 280 K Px = 760 mm, P2 = 740 mm p,r, P2 _ 2.5x280x740 = 2.3 g/litre. P2 = „ P\ 7] 760x300 80. (d) : Suppose the gas removed = x mole The amount remaining in the vessel = (1 - x ) mole Volume is constant and pressure is kept the same under this condition. nlTl = n2T2 Here, nx = 1 mole, n2 = (1 — x) mol r, = 300 K, T2 = 600 K Therefore, 1 x 300 = (1 - x) 600 1 = 2(1 - x ) = 2 - 2x .'. x = 1/2 mole = 0.5 mole. 81. (c) : CH 3 CONH 2 + NaOH
(aq)
CHjCOONa + NH 3 This is also test for amide - (CONH,) group. 82. (d)
(benzaldehyde)
So, toluene is conveniently oxidised with Etard reagent (chromyl chloride CrO,Cl 2 )to benzaldehyde. This reaction is known as Etard reaction. 73. (c) 74. (a): Because it contains maximum number of ions. 75. (c) CHEMISTRY TODAY | JANUARY '06
77. (d) : Pf = 3 atm, P2 = 1 atm, V2 = 2 litres, V2 = ? = (273 + 273) K = 546 K, T2 = 273 K
.,
O
x v0'
Now 15A: = 30 (given) (As volume of C 0 2 is 30 ml) .
76. (d) : Here K, = 20 ml, K, = 20 ml r, = 273 K, T2 = ? Pt = 1 atm, P2 = 2 atm 20x20x273 W _P2V2 i2= 546 K. P\V\ 1x20 T-> 75
83. (c): Reactivity towards nucleophilic substitution lies in the following sequence. RCOCI > (RC0) 2 0 > RCOOR' > RCONH, Nucleophilic substitution takes place readily at an acyl carbon than at saturated carbon. Thus for nucleophilic substitution acid chlorides are more reactive than alkyl chlorides; amides are more reactive than amines and esters
13
are more reactive than ethers. RCOCI > RC1, RCONH 2 > RNH2, RCOOR' > ROR' 84. (c) : Thionyl chloride is the better reagent because the byproducts of the reaction are the gases S0 2 and HCI, which are easily separated. 85. (c)
86. (d) : - NH 2 is an o-, p-directing group, as it has at least one pair of non-bonding electrons on the atom adjacent to the benzene ring.
93. (b) : Benzene sulphonyl chloride (C 6 H 5 S0 2 C1) is known as Hinsberg's reagent, and used for the separation of primary, secondary and tertiary amines. 94. (b): This reaction is used to make distinction between primary, secondary and tertiary amines. 95. (c) : C 6 H 5 NH 2 + CHC13 + 3KOH ( a f c ) -> A Y C 6 H 5 NC + 3KC1 + 3H 2 0 CH 3 COCH 3 + 3C12 CCl 3 COCH 3 + 3HC1 Z
87. (c)
OH
CCljCOCHj
2CHCI
CHjCOO-^
88. (b) : Asgammexane is nothing but C6H6C16 (B.H.C). A1C1, 89. (d) : C 6 H 6 (excess) + CCI4 (C 6 H 5 ) 3 C - CI (C 6 H 5 ) 3 C - CI is called triphenyl methyl chloride.
96. (d)
90. (a) : Reaction —> alkylation Reagent —> R - CI Catalyst
This reaction is called Friedel-Craft's reaction.
Electrophile —>
R
+
CC13C0CH3
- CHjCl
(CH 3 ) 91. (c) : C 2 H 5 NH 2 or R - N H 2 (NaNQ2+HCl) or HN02 (0°C) » C , H 5 O H + N , 92. (d)
97. (c)
;ca
CH,COO'
A1C1,
(benzene)
AICI-,
Product C fi H, - R
Wl-fcG-
C a < ^ OH
CH3
(toluene)
98. (c)
99. (d) : C6H6 + 3C12
bright sunlight (U.V.),
> C6H6C16 (B.H.C) 100. (d) : Coal and petroleum are the two important sources of aromatic hydrocarbons.
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CHEMISTRY TODAY | JANUARY '06
Q h M S ) C B S E ) f D P M T ) A F M C ) f v M M C ) (EAMCET) (WB-JEE) ( B H U
) ( CMC )
2006 Medical Entrance Exam ( M a n i p a l PMT)
Practice Test Paper
{ UP CPMT ) fCET Karnataka]
( JIPMER )
(MP PMT) ( M G I M S ) ( P M P T B i h a r ) (PMT H a r y a n a ) ( K e r a l a P M T ) ( R a j . P M T j f T N P C E E )
1. Iodised table salt contains 7.6 x IO-5 g of KI per gram of NaCl. The concentration in ppm of KI is (a) 76 (b) 152 (c) 500 (d) 760. 2. The heat of combustion of ethane, hydrogen and graphite are -33.0, - 68.5, - 9 4 K cal/mole, the heat of formation of ethane would be (a) - 1 8 8 K cal/mole (b) -383.5 K cal/mole (c) -350.5 K cal/mole (d) +53.5 K cal/mole. 3.
A compound A'reacts in the following ways. X(aq) yellow precipitate
BaC1 2 (aq)^
NaOH (aq) brown precipitate
white ppt.
\
I
NH3 (aq) colourless solution
The compound X is likely to be (a) Pb(N0 3 ) 2 (b) CaCr0 4 (c) Ag 2 S0 4 (d) AgN0 3 . 4. (a) (b) (c) (d)
Holmes calcium calcium calcium calcium
signal makes use of a mixture of carbide and calcium chloride carbide and sodium phosphide carbide and calcium phosphide chloride and sodium phosphide.
5. The oxyacid of phosphorus that has some reducing property is (a) H 3 P0 4 (b) HP0 3 (c) H 3 P0 3 (d) H 2 P 2 0 7 . 6. Portland cement contains the following amount of CaO. (a) 5-15% (b) 20-35% (c) 50-60% (d) 70-80%. 7. The ether that undergoes electrophilic substitution reaction is CHEMISTRY TODAY | DECEMBER '05
(b) C 6 H 5 OCH 3 (d) C 2 H 5 OC 2 H 5 .
(a) CH 3 OC 2 H 5 (c) CH 3 OCH 3 8.
Predict the final product B in the sequence of reaction. CH = CH
(a) CH 3 COONa (c) CH 3 CHO
3 0 % H , S 044
„
> A
HgS04
>B NaOH
(b) CH 3 COOH (d) C H 3 - C H - C H 2 - C H O OH
9. An organic compound with the formula C 6 H ! 2 0 6 forms 20% a yellow crystalline solid when treated with phenylhydrazine and gives a mixture of sorbitol and mannitol when reduced with sodium. Which among the following could be the compound? (a) fructose (b) glucose (c) mannose (d) sucrose. 10. Caprolactum polymerises to give (a) terylene (b) teflon (c) glyptal (d) nylon-6. 11. The S N 1 mechanism for the hydrolysis of an alkyl halide to an alcohol involves the formation of (a) carbanion (b) carbocation (c) free radical (d) pentavalent carbon in the transition state. 12. The relationship between standard reduction potential of cell and equilibrium constant is shown by (a) E°,cell
" log Kc (b) / ^ — - l o g / Q . 0.059 (c) £°cen = 0.059 n log/Q; ,,,
( d )
'
r-o _ 'og cell n
£
13. Colourless solutions of the following four salts are placed separately in four different test tubes and a strip of copper is dipped in each one of these. Which solution will turn blue? (a) KN0 3 (b) AgN0 3 47
(c) Zn(N0 3 ) 2 14. and (a) (c)
(d) ZnS0 4 .
[Fe(H20)5N0]S04
Concentrated H 2 S0 4 has a density of 1.98 gm/ml is 98% H 2 S0 4 by weight. Its normality is 2N (b) 19.8 N 39.6 N (d) 98 N.
15. Which of the following reactions occur at the cathode during the charging of lead storage battery? (a) Pb 2+ + 2e~ Pb (b) Pb 2+ + S0 4 2 " PbS0 4 2+ (c) Pb H> Pb + 2e~ (d) PbS0 4 + 2H 2 0 -> Pb0 2 + 4H + + S0 4 2 " + 2e~ 16. The number of dative bonds in sulphuric acid molecule is (a) 0 (b) 1 (c) 2 (d) 4. 17. The correct sequence of decrease in the bond angle of the following hydrides is (a) NH 3 > PH3 > AsH 3 > SbH3 (b) N H 3 > ASH3 > P H 3 >
(c) SbH3 >
SbH3
18. (a) (b) (c)
Which C(„ + CW + CH 4 w
of the following reactions is not exothermic? 02te)->C02te) 2SW.-»CS2W + 20 2 -> C 0 2 w + 2H 2 0 m
(d)
C O
+ 1/2
19. (a) (b) (c) (d)
The favourable conditions for Haber's process are low temperature and low pressure low temperature and high pressure high temperature and low pressure high temperature and high pressure.
0
2 W
- 4 C 0
log K
•
t
t
log K
log K
1 IT
•
1/7"
•
(d) 1/7"
•
with Cu and traces of with Zn and traces of with Ca and traces of
*
[S]
-HBr .
contains an asymmetric carbon
[D] (alkene)
ozonolysis
>
[C]
-co.
(No geo. isomerism) ^
(positive S c h i f f s test)
^
[yr]
(negative S c h i f f s test)
(E) and (F) are
2 ( S )
(a)
(C)
Br,/P
(C5H10O2)
t 1/7"
with Fe and traces of
24. In the reaction,
SbH3.
20. A graph plotted between logKvs 1/7"for calculating activation energv is shown by
21. The oxidation number of Fe in compound 46
23. 'Mischmetal' is an (a) alloy of rare earth elements S, C, Ca and Al (b) alloy of rare earth elements S, C, Ca and Al (c) alloy of rare earth elements S, C, Ca and Al (d) alloy of transition elements S, C, Ca and Al.
[A]
PH3 > N H 3 > ASH3 >
W
(b) - 2 (d) +1.
22. The equivalent weight of sodium thiosulphate (Na 2 S 2 0 3 -5H 2 0) in the reaction 2Na 2 S 2 0 3 + I 2 -> 2NaI + Na 2 S 4 0 6 is (a) 248 (b) 124 (c) 596 (d) 62.
ASH3 > PH3 > N H 3
(d)
js
(a) +2 (c) 0
O II (a) HCHO and CH3 - C - C2H5 O II (b) HCHO and CH3 - C - CH3 CH
(C)
CH
CH • COOH and HCHO
(d) none of these. 25. The amount of NH 3 and NH4C1 required to prepare a buffer solution of pH = 9, when (pKh for NH 3 = 4.7, log2 = 0.30) (a) 0.2 mol/lit and 0.4 mol/lit (b) 0.4 mol/lit and 0.2 mol/lit (c) 0.2 mol/lit and 0.2 mol/lit (d) 0.2 mol/lit and 0.02 mol/lit. 26. Ka for ascorbic acid (HASC) is 5 * 10~5. Then the value of [H+] in an aqueous solution in which the concentration of ASC~ ions is 0.02 (M) will be (a) 5 x 10~7 (b) 5 x IO"9 CHEMISTRY TODAY | DECEMBER '05 47
(c) 5 X 10-
(d) 1 x 10"
27. The increasing order of thermal stability for oxyhalide anion/the salts of CIO", C102", C103", C104" is as follows. (a) CIO < ClOY < C10 3 - < C10 4 (b) c i o - > c i o 2 - > d o , - > c i o 4 (c) CIO" > C10 4 - < C10 2 < CIO3(d) C10 4 " > C10 2 - > CIO- > CIO328. Which of the following will displace Br, from an aqueous solution containing bromide ions? (a) Cl 2 (b) I 3 (c) I 2 (d) Cl". 29. Ionic solids with Schottky defects contain in their structure (a) equal number of cationic and anionic vacancies (b) anionic vacancies and interstitial ions (c) cationic vacancies (d) cationic vacancies and interstitial cations. 30. will (a) (c)
Which one of the following pairs of atoms or ions have identical ground state electronic configuration? Li + and He" (b) Cl" and Ar Na and K (d) F + and Ne.
31. A compound is treated with NaNH 2 to give sodium salt. Identify the compound. (a) C 2 H, (b) C 6 H 6 (c) C 2 H 6 (d) C 2 H 4 . 32. Chlorobenzene reacts with Mg in dry ether to give a compound (/I) which further reacts with ethanol to yield (a) phenol (b) benzene (c) ethyl benzene (d) phenyl ether. 33. Benzene reacts with n-propyl chloride in the presence of anhydrous A1C13 to give (a) 3-propyl-l-chlorobenzene (b) /7-propyl benzene (c) no reaction (d) isopropylbenzene. 34. the (a) (c)
At 90°C, pure water has [H+] = IO"6. What will be value of Kw at 90°C? IO"12 (b) IO"11 8 10~ (d) 10-6.
35. A solution of potassium bromide is treated with each of the following. Which one will liberate bromine? (a) hydrogen iodide (b) sulphur dioxide (c) chlorine (d) iodine.
C H E M I S T R Y T O D A Y | DECEMBER '05
36. If a 0.1 molar solution of glucose (mol. wt. = 180) and a 0.1 molar solution of urea (mol. wt. 60) are placed on the two sides of a semipermeable membrane to equal heights, then it will be correct to say that (a) there will be no net movement of solutions across the membrane (b) glucose will flow across the membrane into urea solution (c) urea will flow across the membrane into glucose solution (d) water will flow from urea solution into glucose solution. 37. The reaction of toluene with chlorine in presence of ferric chloride gives mainly (a) «-chlorotoluene (b) benzyl chloride (c) o- and p- chlorotoluene (d) benzoyl chloride. 38. A solution containing ammonium chloride and sodium nitrite on boiling produces (a) ammonia (b) nitric oxide (c) nitrogen (d) nitrous oxide. 39. In the manufacture of bromine from sea water, the mother liquor containing bromides is treated with (a) carbon dioxide (b) chlorine (c) iodine (d) sulphur dioxide. 40. When chlorine is passed over dry slaked lime at room temperature, the main reaction product is (a) Ca(C10 2 ) 2 (b) CaCl 2 (c) CaOCl 2 (d) Ca(OCl) 2 41. C (a) (c)
In a molecule of carbon tetrachloride the four Cl bonds are directed towards the corners of a square (b) tetrahedron prism (d) cube.
42. Cu 2+ and Ag + are both present in the same solution. To precipitate one of the two ions and leave the other in solution, we shall add (a) HCl (fl?) (b) N H 4 N 0 3 (aq) (c) H 2 S {aq) (d) H N 0 3 ( a q y 43. H2, (a) (b) (c) (d)
The root mean square speeds at S.T.P. of molecules N 2 , 0 2 and HBr are in the order of N 2 > 0 2 > HBr > H 2 0 2 > N 2 > H 2 > HBr HBr > 0 2 > N 2 > H 2 H 2 > N 2 > 0 2 > HBr. 47
44. Which one of the following carboxylic acids will have lowest acidic strength? (a) BrCH,COOH (b) CH 3 COOH (c) CHjCHCICOOH (d) ClCH 2 COOH. 45. The hydrolysis of PC13 produces (a) (H 3 P0 3 + HCl) (b) (PH3 + HCIO) (c) (H 3 P0 3 + HCIO) (d) (H 3 P0 4 + HCl). 46. Calcium carbonate decomposes on heating according to the equation : CaC0 3 = CaO + C0 2 . At S.T.P. the volume of C 0 2 obtained by thermal decomposition of 50 g of CaC0 3 will be (a) 22.4 litres (b) 44 litres (c) 11.2 litres (d) 1 litre. 47. 12.5 ml of a gaseous hydrocarbon were mixed with 100 ml of oxygen and exploded. After cooling the residual gas occupied 68.75 ml. The volume was further reduced by 50 ml by passing the gases in KOH solution and the remaining gas was oxygen. The molecular formula of the hydrocarbon is (a) C 2 H 6 (b) C 4 H 8 (c) C 4 H, 0 (d) C 5 H 12 . 48. Two containers A and B contain the same the pressure, volume and absolute temperature in A are two times as compared to those in B density of gas in A is d, then density of gas in (a) d/2 (b) d (c) 2d (d) 4d.
gas. If of gas and if B is
49. XC + THN0 3 C 0 2 + N 0 2 + H 2 0. The value of X and Y to balance this equation is (a) X=4, Y= 3 (b) X= 3, 7 = 4 (c) X=4, 7 = 1 (d) X = 1, Y = 4. 50. The compound which gives the most stable carbonium ion on dehydration is (a) 2-methyl-l-propanol (b) 2-methyl-2-propanol (c) 1-butanol (d) 2-butanol. SOLUTIONS 1. 2.
48
[C w + 0 2 to - » CP 2 to ; 1 1 T J3H n 2C' (,, - w022 C 2 H g + — 0 2 ; AH= +33 Kcal/mol 2C w + 3H2 w -> C 2 H 6 ^y, AW" = -350.5 Kcal/mol. 3. (d) : Reaction with KI and NaOH indicate that cation is Ag + . i.e. Ag+ + KI —> Agl + K + yellow ppt.
Ag+ + NaOH
AgOH + Na + brown
Reaction with BaCl 2 indicate that anion is either S0 4 2 ^ or N0 3 " as white ppt. may be formed due to BaS0 4 or AgCl. However, AgCl is soluble in NH 3 and not BaS0 4 , so X is AgN0 3 . 4.
(c)
5. (c): Oxyacid in which P is in low valent oxidation state can act as reducing agent. Oxidation state of P in H 3 P0 4 = +5 Oxidation state of P in HP0 3 = +5 Oxidation state of P in H 3 P0 3 = +3 Oxidation state of P in H 4 P 2 0 7 = +5 As oxidation state of P in H 3 P0 3 is +3, hence it can be oxidised to +5, thus shows some reducing behaviour. 6. (c) : Composition of Portland cement is CaO - 60%, Si0 2 - 22.5%, A1203 - 7.5%, MgO - 2.5%, Fe 2 0 3 - 2.0%, K 2 0 - 1.5%, S 0 3 - 1.0%, Na 2 0 - 1.5%. Essentially,
5
(a) : 7.6 x 10' g in one gram = 7.6 x 10~5 x 106 = 76 ppm. 7 (c) : C 2 H 6 w + - 0 2 (g) ( g ) -> 2C0 2 2 ' AH = - 3 3 . 0 Kcal/mol I ; H2(g) + 2 02(g)- H 2 0
AH = -68.5 Kcal/mol ... (ii) c (.«) + ° 2 (g) c o 2 fe) AH = - 9 4 Kcal/mol ... (iii) Heat of formation of ethane is given by 2C (.V) 3H 2 0 (,,) —» C 2 H 6 (g), AH, = ? The above equation can be obtained by multiplying equation (ii) by 3 and equation (iii) by 2, and then subtracting (i) from the resultant equation (iv). 1 ; AH = -68.5] x 3 [H2 fe) - 0 2 to H 2 0
% SiO-,
• = 2.5 to 4.0
% AI 2 O 3
% CaO - = 1.9 to 2.1 % SiO, + %A1,0, + %Fe,0, 7. (c) : Aromatic ring undergoes electrophilic substitution reaction due to rich Jt-electron cloud in the ring. CHEMISTRY TODAY | DECEMBER '05 47
8.
(D) : C H =
CH
3 0 % H
*S(S
it is reduced to Ag. Cu is oxidised to Cu : " ion.
CH,CHO
HgSQ4
CH, - CH - CH,CHO
14. (c) : 98% H 2 S0 4 by weight means =
I
OH
B
(aldol)
9.
(a): CH,OH
CH =
I C= o I
C =
I
NNHCSH5
(CHOH)3
CH 2 OH
CH 2 OH fructose osazone (yellow)
CH 2 OH [H]
>
H - C - O H
CH2OH
I
+
H O - C - H
(CHOH)3
(CHOH) 3
CH 2 OH
CH 2 OH mannitol
sorbitol
10. (d) 11. (b) : S N 1 mechanism. > R+ + X~ > RQH+X" (carbocation) 12. (b) : AG = -nFE Cell reaction at equilibrium has AG = 0. This means, nFE = 0 or, E = 0. Consider a reaction, [Zn 2+ ] Zn + Cu 2+ ^ Zn 2+ + Cu, .-. K = [Cu 2+ ] As only ions are present in solution, then RX
E-E°
eeU
ce
"
+
3L]og I C O nF g c [Zn 2+ ]
nF
[Zn 2+ ]
nF
[Cu 2+ ]
RT, ,„ 2.303/?7\ £0ce.i = — log. K = — log10 K nF nF £°ce„=^log,o^(at298K) n Also, nFE° = RT logeK or, -AG° = RT log e K. 13. (b) : Cu + 2AgN0 3 Cu(N0 3 ) 2 + 2Ag colourless green As, Ag is below the Cu in electrochemical series, hence CHEMISTRY TODAY | DECEMBER '05
N, 2S 4 " °
NNHQH,
(CHOH) 3
fructose
Volume of solution =
100
98 g H,S0 4 100gwater
100
d 1.98 g eq. of H 2 SQ 4 98 volume of solution 49x100 1.98x1000
JVH2so4 = 19.8 x 2 = 39.6 15. (d) OH
16. (a) :
0 =
S = 0
I OH
17. (a) : This is due to decreased bond-bond repulsions as electronegativity of X decreases. 18. (b) : All combustion reactions are exothermic. 19. (b) : Formation of NH 3 proceeds with decreasing of moles of products, hence pressure decreases. It is an exothermic reaction. According to Le-Chatelier principle, to counter the physical changes during reactions, high pressure and low temperature is required. However, at very low temperature rates of reaction decreases considerably, hence reaction is carried out at optimum temperature at the expense of yield. 20. (a) : In K = A + j
or, 2.303 log K = A + j
1 log K vs — is linear with a positive slope. 21. (a) : Oxidation number of Fe in compound [Fe(H 2 0) 5 N0]S0 4 will be as follows x + (0 x 5) + (0 x 1) + 1 x (-2) = 0 => x = +2. Hence, oxidation state of Fe in compound [Fe(H 2 0) 5 N0]S0 4 will be +2. 22. (a) : The molecular weight of hydrated sodium thiosulphate (Na 2 S 2 0 3 -5H 2 0) is 248. From reaction, 2Na 2 S 2 0 3 + I2 2NaI + Na 2 S 4 0 6 it is clear, that change in oxidation number = 5 - 4 = 1 mol. wt. Now, E (Na 2 S 2 0 3 ) = c h a n g e i n 0 . N 248
248
5-4
1
= 248.
47
23. (a) : 'Mischmetal' is an alloy of rare earth elements with iron and traces of S, C, Ca and AI. It is used to improve the workability of steel. 24. (b) : The reaction is C I
S CO + HCHO 0.3 = log]0 (0.6- x) 0.6-x log l0 2 = log,0 ——^ => 2 = — ^ 0.6-x 0 . 6 -x => x = 0.4 .-. Concentration of [NH3] = 0.2 mol/lit. and concentration of [NH4C1] = 0.4 mol/lit.
C 2 H 5 OH + C 6 H 5 MgCl
(benzene)
33. (d)
+ CH3CH,CH2C1
a
=>
26. (b) : Kh =
1x10"-14
A'
= 2x10"
Ka 5x10" Hydrolysis reaction, ASC~ At equilibrium
+ OH-
HA
x
(0.02 - x)
C6H6 + Mg
A1C1,
OC2HS Cl
^
CH33
I
CH-CH,
+ HCl
34. (a) : As [H+][OH"] = Kw But, [H+] = [OH - ] = 10"6 [10 6 ][10- 6 ] = IO 1 2 =
35. (c) : Because, chlorine is more electronegative than bromine. Therefore, it can replace bromine in KBr. 2KBr + Cl2 2KC1 + Br2 36. (a) : Such solutions are said to be isotonic.
= 0.02
Now by applying the formula, K,=-
0.02
0.02
2x10"
=-
0.02
=> x 2 = 2 x IO"10 x 0.02 = 2 x IO"10 x 2 x io- 2 =i» x 2 = 4 x IO"12 => x = 2 x 10"6 => [OH-] = 2 x 10-6. ...
+
9
] = l i l i ^ - = 5xlO- . 2x10" [Since, [H+] x [OH"] = 1 x IO"14]. [H
27. (a) : As, the thermal stability of both the acids and their salts increases with the increasing order of oxidation 50
38. (c) : NH4C1 + NaN0 2 39. (b) : 2KBr + Cl2
N 2 + NaCl + 2H z O
2KCI + Br2
40. (c) : Ca(OH) 2 + CI2
CaOCI2 + H 2 0
41. (b) : In carbon tetrachloride covalent bonding involves sp3 hybridisation. So C - Cl bonds are directed towards four corners of a tetrahedron. CHEMISTRY TODAY | DECEMBER '05
42. (a): Silver will be precipitated in 1 st group as silver chloride on addition of HCI.
1 vol
43. (d): Because, the root mean square speed is inversely proportional to the square root of molecular weight.
12.5 ml
44. (b): Presence of halogen in the alkyl chain enhances the acidic strength by increasing the ionisation of carboxylic group due to inductive effect.
47. (c) : Volume of hydrocarbon taken = 12.5 ml Volume of oxygen taken = 100 ml Volume of C 0 2 produced = 50 ml Volume of oxygen left = (68.75 - 50.00) ml = 18.75 ml Volume of 0 2 reacted with hydrocarbon = (100 - 18.75) = 81.25 ml Let t h e f o r m u l a of t h e h y d r o c a r b o n b e CX¥LY C H, +
x
O, - > X C 0 2 + ^ H 2 0
12.5| x + ^
| ml
12.5* ml 50
115
Here, 12.5.x = 50
„
Again, 12.5| x + ^ ( = 81.25
45. (a) : Hydrolysis o f P C l 3 PC1, + 3HOH H 3 P0 3 + 3HC1. 46. (c) : CaC0 3 = CaO + CO, (40 + 12 + 48) g 22.4 litres at STP v 100 g CaC0 3 produces 22.4 litres C 0 2 at STP .'. 50 g CaC0 3 will produce 11.2 litres C 0 2 at S.T.P.
x vol
vol
12.5| 4 + ^ | = 81.25
= 10
Therefore, formula of the hydrocarbon = C 4 H I 0 . 48. (b) : PA = 2PB, dA = d, TA = 2TB, Pj
VA = 2VB,
dB = ?
P
As, we know that —— = —— d,7]
d T
d T
AA
BB
a2T2
2 PR . - J j L d x 2 Tb dBTB
dH = d. 49. (d) : By trial and error method, we can get x = 1 and y = 4. 50. (b)
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C H E M I S T R Y T O D A Y | DECEMBER '05 47
47
42. (a): Silver will be precipitated in 1 st group as silver chloride on addition of HCl.
1 vol
i
43. (d): Because, the root mean square speed is inversely proportional to the square root of molecular weight.
12.5 ml
12.5
44. (b): Presence of halogen in the alkyl chain enhances the acidic strength by increasing the ionisation of carboxylic group due to inductive effect.
x +
^ I vol
x+ — \
Here, 12.5* = 50
47. (c) : Volume of hydrocarbon taken = 12.5 ml Volume of oxygen taken = 100 ml Volume of C0 2 produced = 50 ml Volume of oxygen left = (68.75 - 50.00) ml = 18.75 ml Volume of 0 2 reacted with hydrocarbon = (100 - 18.75) = 81.25 ml Let the formula of the hydrocarbon be CVH,. CrHv +
• x C 0 22 + ^ H 22 0
2
Wl-fcG"
ml
x =
vol
12.5A m l
,
50
12.5
=4
Again, 12.5| x + ^ | = 81.25
45. (a) : Hydrolysis of PC13 PC13 + 3HOH H3PO3 + 3HC1. 46. (c) : CaCOj = CaO + C0 2 (40 + 12 + 48) g 22.4 litres at STP 100 g CaCO, produces 22.4 litres C0 2 at STP .-. 50 g CaCOj will produce 11.2 litres C0 2 at S.T.P.
X
12.51 4 + —1 = 81.25
_y = 10
Therefore, formula of the hydrocarbon = C 4 H ]0 . 48. (b) : PA = 2PB, dA = d, Ta = 2Tb, Va = 2 Vb, dB = ?
P P As, we know that —— = —— d T d\T\ ii 2PB Pa _ PB A A B B dx2Tg => dB = d. d
T
d
T
PB
dBTB
49. (d) : By trial and error method, we can get x = 1 and y = 4. 50. (b)
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gg
•
rap*-, •
Rs.200 'li '" 1 C H E M I S T R Y T O D A Y | DECEMBER '05 47
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47
SOLVED PAPER
K E R A L A PMT - 2005 1. The silver salt of an unknown monoacidic alkyne contains 67.08% silver. The structure of the alkyne is (a) H 3 C - CH 2 - C = CH (b) H 3 C - C = CH (c) HC = CH (d) H3C - C = C - CH 3 (e) either (c) or (d). 2. Match list I with list II and select the correct answer using the code given below the lists. List I
List II
(mixture) 1. o- and p-nitrophenols 2. Naphthalene and urea 3. Heptane and octane 4. Benzene and nitrobenzene
A. B. C. D.
(method for separation) Azeotropic distillation Steam distillation Simple distillation Sublimation
E. Gas chromatography Codes :
(a) 1-A, 2-D, 3-E, 4-C (b) 1-B, 2-D, 3-C, 4-E (c) 1-B, 2-D, 3-E, 4-C (d) 1-C, 2-E, 3-D, 4-A (e) 1-E, 2-D, 3-C, 4-A. 3. 0.4 g of a silver salt of a monobasic organic acid gave 0.26 g pure silver on ignition. The molecular weight of the acid is (atomic weight of silver = 108) (a) 58 (b) 72 (c) 90 (d) 104 (e) 124. 4. Consider the parallel reactions in the electrophilic addition of HBr to propene via the alternative pathways shown below. path 1 (with peroxide)
^
Propene + HBr path 2 (without peroxide)
1-bromopropene + 2-bromopropene (4) (S) Identify the wrong statement with reference to the above. (a) path 1 has predominance of (A) over (B) (b) path 2 has predominance of (B) over (A) (c) path 1 is in accordance with anti-Markownikoff's rule (d) path 2 follows Markownikoff's rule (e) both the paths afford 50% yield of (A) and (B). 189
5. Relative stabilities of various alkenes represented as R 2 C = CR2, R 2 C = CHR, RCH = CHR (trans), RCH — CHR (cis) are in the increasing order of (a) R2C = CR2, R2C = CHR, RCH - CHR (trans), RCH = CHR (cis) (b) R 2 C = CR 2 , R 2 C = CHR, RCH = CHR (cis), RCH = CHR (trans) (c) RHC = CHR (trans), RCH = CHR (cis), R 2 C = CHR, R 2 C = CR 2 (d) RHC = CHR (cis), R,C = CR 2 , R 2 C = CHR, RCH = CHR (trans) (e) R2C = CR2, R2C = CHR, RCH = CHR (trans), RHC = CHR (cis) 6. Gasoline with an octane number of 90 is equivalent in knocking characteristics to a mixture of heptane and isooctane of the following composition. (a) 20% heptane + 80% iso octane (b) 90% heptane + 10% iso octane (c) 80% heptane + 20% iso octane (d) 10% heptane + 90% iso octane (e) 5% heptane + 95% iso octane. 7. Consider the following carbocations. 1. C13C+ 2. CI,CH + 3. C1CH2+ 4. CH 3 + . The stability sequence follows the order (a) 4 < 1 < 2 < 3 (b) 1 < 2 < 3 < 4 (c) 4 < 1 < 3 < 2 (d) 4 < 2 < 1 < 3 (e) 4 < 3 < 2 < 1 8. Which of the following is dehydrohalogenated readily at the highest rate? Br -Br (a)
(b)
Br (c)
Br (d)
Br (e) 9. Which one of the following statements about the nitrogroup in organic compounds is not correct? CHEMISTRY TODAY | DECEMBER '05 47
(a) the N atom is sp2 hybridised (b) the N atom forms a N = O bond and a N —> O bond (c) the two nitrogen-oxygen bond lengths are different (d) it exists in two canonical forms (e) the nitrogen atom carries a formal charge of +1. 10. (a) (c) (d) (e)
Which one of the following molecules is achiral? l-bromo-2-butene (b) 3-bromo-l-butene 2,3-dihydroxy propanal 2-hydroxypropanoic acid 2-chlorobutane.
11. has (a) (e)
The simplest acyclic alkane containing a chiral atom a vapour density of 50 (b) 45 (c) 90 (d) 100 75.
12. Given below are conformations of butane. Which conformation is the most stable? (a) staggered : anti (b) methyl-hydrogen eclipse (c) hydrogen-hydrogen eclipse (d) staggered : Gauche (e) methyl-methyl eclipsed. 13. The raw materials for the commercial manufacture of DDT are (a) chlorobenzene and chloroform (b) chlorobenzene and chloromethane (c) chlorobenzene and chloral (d) chlorobenzene and iodoform (e) chlorobenzene and BHC. 14. Iodoform cannot be prepared by reacting which of the following with NaOH and iodine? (a) CHjOH (b) CH 3 CH 2 OH (c) CH 3 CHO (d) (CH 3 ) 2 CO (e) (CH 3 ) 2 CHOH. 15. Identify C in the following scheme. CH3CH2CH2OH
PC ?
'
> A
ALC KQH
-
>
If diazotisation of aniline is carried out at 30°C, main organic product formed is phenol (b) phenyl isocyanide diphenyl amine (d) phenyl hydrazine nitrosobenzene.
19. (a) (b) (c) (d) (e)
Give the monomers of nylon-66. butadiene and acrylonitrile ethylene glycol and terephthalic acid hexamethylene diamine and adipic acid melamine and formaldehyde phenol and formaldehyde.
20. CH33CHO + HCHO Ni 2+ > Cr 3+ > Fe 3+ (b) Cr 3+ > Fe 3+ > Ni 2+ > Cu 2+ (c) Fe3+ > Cr 3+ > Cu 2+ > Ni 2+ (d) Ni 2+ > Cu 2+ > Fe 3+ > Cr 3+ (e) Fe 3+ > Cr 3+ > Ni 2+ > Cu 2+ . 47. Which of the following forms colourless compounds? (a) Sc 3+ (b) V 3+ (c) Ti3+ (d) Cr 3+ (e) Fe 2+ . 48. Find the magnetic moment of a divalent ion in aqueous solution if its atomic number is 25. (a) 3.9 B.M. (b) 4.9 B.M. (c) 5.9 B.M. (d) 6.9 B.M. (e) 7.9 B.M. 49. in the nuclear fusion ?H + ?H 193
, H e , the masses
of ^H and jHe are 2.014 mu and 4.003 mu respectively. The energy released per atom of helium formed is MeV. (a) 16.76 (b) 26.38 (c) 13.26 (d) 9.31 (e) 23.275 50. In successive emission of p and a particles, how many (3 and a particle should be emitted for the natural (4n + 1 series) conversion of 94 Pu 241 to 92 U 233 ? (a) a , p (b) a , 2p (c) 2a, 3P (d) 2a, P (e) 2a, 20. 51. What will be the binding energy of 1S 0, if the mass defect is 0.210 amu? (a) 1.89 x 1016 J mol"1 (b) 1.89 * 1015 J mol"1 (c) 1.89 x 1014 J mol' 1 (d) 1.89 x 1013 J mol"1 (e) 1.89 x io 1 2 J mol"1. 52. Match the list 1 and II and pick the correct matching from the codes given below. List 1
A.
List II
(dE/dV) 7. = 0
B. JV=-AE C. AE=0 D. AG° E.
(dT/8P)H*
(a) (b) (c) (d) (e)
A-2, A-2, A-3, A-5, A-5,
B-l, B-5, B-l, B-4, B-3,
0 C-4, C-l, C-2, C-l, C-l,
D-5, D-4, D-5, D-2, D-2,
1.
Isothermal process
2. 3. 4.
-nFE° Adiabatic reaction van der Waal's gas
5.
Ideal gas
E-3 E-3 E-4 E-3 E-4.
53. The heats of neutralisation of HCl with NH 4 OH and NaOH with CH 3 COOH are respectively -51.4 and -50.6 kJ eq' 1 . The heat of neutralisation of acetic acid with NH 4 OH will be (a) -44.6 kJ eq~' (b) -50.6 kJ eq"1 1 (c) -51.4 kJ eq" (d) -57.4 kJ eq"1 1 (e) - 7 0 . 2 kJ eq" 54. Five moles of a gas is put through a series of changes as shown t graphically in a cyclic \ process. The process during i A -H> B, B C and C A respectively are (a) isochoric, isobaric,
temperature
isothermal
CHEMISTRY TODAY | DECEMBER '05 47
(b) (c) (d) (e)
isobaric, isochoric, isothermal isothermal, isobaric, isochoric isochoric, isothermal, isobaric isobaric, isothermal, isochoric.
55. For the hypothetical reactions, the equilibrium constant (K) values are given. A ^ B ; = 2.0 B C ; k2 = 4.0 C ^ D • k3 = 3.0 The equilibrium constant (X) for the reaction A ;=± D is (a) 48 (b) 6 (c) 2.7 (d) 12 (e) 24. 56. The Ka values of formic acid and acetic acid are respectively 1.77 x 10"4 and 1.75 * 10"5. The ratio of the acid strength of 0.1 N acids is (a) 10 (b) 3.178 (c) 0.3 (d) 0.1 (e) 100. 57. Equal volumes of the following Ca2+ and F" solutions are mixed. In which of the solutions will precipitation occur? (K,p of CaF 2 = 1.7 x IO"10) 1. IO"2 M Ca 2+ + IO"5 M F" 2. 10-3 M Ca 2+ + 10"3 M F" 3. 10"4 M C a 2 + + 10-2 M F4. 10"2 M C a 2 + + 10-3 M F" Select the correct answer using the codes given below, (a) in 4 only (b) in 1 and 2 (c) in 3 and 4 (d) in 2, 3 and 4 (e) in all. 58. Which of the following solutions are isotonic with one another? 1. 0.15 M urea 2. 0.05 M CaCl 2 3. 0.1 M M g S 0 4 4. 0.15 M glucose. Select the correct answer using the codes given below, (a) 1 and 4 (b) 2 and 3 (c) 1, 2 and 4 (d) 2, 3 and 4 (e) 1, 2, 3 and 4
in freezing point of water is (given K} of water = 1.86 K m o H kg and specific gravity of ethylene glycol is 1.11) (a) 0.0033 (b) 3.33 (c) 0.333 (d) 0.033 (e) 33.3 61. It costs Rs. 10 to electro deposit 1 g of Mg from a solution of MgS0 4 . The cost of electro depositing of 1 g of Al from A12(S04)3 solution at the same temperature is (atomic weight of Mg = 24, Al = 27) (a) Rs. 10 (b) Rs. 6.66 (c) Rs. 13.33 (d) Rs. 8.4 (e) Rs. 9.6 62. Identify the wrong statement. (a) The oxidation potential for E°2s°c F2/2F~ being the highest of+2.85 V makes the halogen the strongest oxidizing agent. (b) Li A1H4 is the best reducing agent in organic synthesis for E°25°c Li + /Li system is - 3 . 0 5 V. (c) HC10 4 is a powerful reducing agent because the oxidation state of chlorine atom is as high as +7. (d) A cotton piece dipped in spirit catches fire in Mn 2 0 7 due to the highest oxidation state of the metal. (e) Manganese atom in Mn0 4 " has a high +ve oxidation state that allows charge transfer transition, imparting a dark violet colour. 63. the (a) (c) (e)
How many coulombs of electricity are required for reduction of 1 mol of Mn0 4 ~ to Mn 2+ ? 96500 C (b) 1.93 x 105 C 5 4.83 x 10 C (d) 9.65 x 106 C 5 5.62 x 10 C.
64. The experimental rate law for a reaction 2A + 2B —> products, is F P > R (a) P> Q> R (d) R>Q>P (c) P> R> Q (e) P = Q = R as the initial and final states are same. 68. 10" 4 g of gelatin is required to be added to 100 cm 3 of a standard gold solution to just prevent its precipitation by the addition of 1 cm 3 of 10% NaCl solution to it. Hence, the gold number of gelatin in mg is (a) 10 (b) 1.0 (c) 0.1 (d) 0.01 (e) 0.001 69. Which one of the following will have the highest coagulating power for a ferric hydroxide sol? (a) NaCl (b) BaCl 2 (c) K 2 C r 0 4 (d) K 3 [Fe(CN) 6 ] (e) [K 4 [Fe(CN) 6 ], 70. Match list I and II and pick the correct matching from the codes given below. List I List I I (complex) (structure and magnetic moment) A. [Ag(CN) 2 ]1. Square planar and 1.73 BM B. [CU(CN) 4 ] 3 " 2. Linear and 0 C. [Fe(CN) s ] 3 3. Octahedral and 0 D. [ C U ( N H 3 ) 4 ] 2 + 4. Tetrahedral and 0 E. [Fe(CN) 6 ] 4 5. Octahedral and 1.73 BM. (a) A-2, B-4, C-5, D - l , E-3 (b) A-5, B-4, C - l , D-3, E-2 (c) A - l , B-3, C-4, D-2, E-5 (d) A-4, B-5, C-2, D - l , E-3 (e) A-4, B-2, C-5, D-3, E - l .
71. The number of chloride ion/s produced by comple: tetraamminedichloroplatinum(IV)chloride in an aqueou solution is (a) four (b) two (c) one (d) three (e) none of these. 72. due (a) (c) (e)
The blue colour obtained in the Lassaigne test is to formation of the compound Na 4 [Fe(CN) 6 ] (b) NaCN Fe 3 [Fe(CN) 6 ] 4 (d) Fe 4 [Fe(CN) 6 ] 3 Fe 4 [Fe(CN) 6 ],
SOLUTIONS X 1. (a) : Let the structure of silver salt be R - C = C - Ag. The mass of silver salt which contains 108 g of Ag = - i ° ° - x ! 0 8 = 161
67.08 .-. R - (12 + 12 + 108) = 161 R = 161 - 132 = 29 or, R = C 2 H 5 Thus the structure of alkyne is CH 3 CH 2 C = 1.e. butyne-1. 2.
CH.
(c)
3. (a) : Mass of silver salt = 0.4 g Mass of silver = 0.26 g Eq. mass of silver salt _ mass of silver salt Eq. mass of silver
mass of silver
0.4 Eq. mass of silver salt = —— x l 0 8 0.26
0.4 E + 107 = ~ ~ r x 108 0.26 4.
E = 59.15 (most probable answer is (a)). (e) : In case of path 1: peroxide Br I CH3CH,CH2Br + CH3CHCH3 l-bromopropane 2-bromopropane (major product) (minor product)
In case of path 2:
/
CHXH — CH, + H+
^t CH3CH2CH, ° carbocation (less stable) CH3CHCH2 2° carbocation (more stable)
Br~
Br~
CH3CH,CH,Br 1-bromopropane (minor product) ' CH3CHBrCH3 2-bromopropane (major product)
195
CHEMISTRY TODAY | DECEMBER '05 47
5. (b): A more substituted alkene is more stable than less substituted alkene owing to higher number of resonating forms. The following order of stability exists in the alkenes. R\ /R R\ /R > yC=C -H H R R/ R R cis R\ /H H\ /H Rv. /H > = C < > > = C < H H H R 6. (d) : The octane number of a given sample may be defined as the percentage by volume of iso-octane present in a mixture of iso-octane and heptane which has the same knocking performance as the fuel itself. Octane number 90 means given sample has the knocking performance equivalent to a mixture containing 90% iso-octane and 10% heptane. 7. (b): The stability of carbonium ions is influenced by both resonance and inductive effects. The groups like - N 0 2 and CI (electron attracting) which have -I-effect reduce the stability of carbonium ions.
• a
Br
(d):
12. ( a ) :
H^f^H Relative energy
Relative energy
CH 3
W
T H
Staggered or Anti
Gauche or S k e w
0.0 kJ mol" 1
3.35 kJ m o l - 1
Partially eclipsed
Fully eclipsed
12.13 kJ mol" 1
15.06 kJ mol" 1
As evident from their relative energies, the decreasing order of the stability of these conformation follows the sequence : staggered > gauche > partially eclipsed > fully eclipsed. 13. (c) : CCl 3CHO + H chloral
CI
H--C1
B r
gives the
most stable product.
^
The two nitrogen-oxygen bond lengths are not different as in canonical structures, there is only delocalisation of electrons without shifting any atoms. OH I* 10. (d) : CH, - C - COOH
dichlorodiphenyltrichloroethane (DDT)
14. (a): Methyl alcohol does not respond to the iodoform test. Iodoform test is exhibited by ethyl alcohol, acetaldehyde, acetone, methyl ketone and those alcohols which possess CH 3 CH(OH) - group. 15. (c) : CH3CH2CH2OH CH3CH — CH?
PCI
alc KOH
^CH 3 CH 3 22CH,C1— 2 (A)
H + HSO,
HSO, CH.CHCH, 3|
3
OH
11. (a): The simplest acyclic alkane containing a chirai H I* carbon atom would be CH, - C - CH,CH,CH,. I CH,CH3 Molecular wt. of this compound = 1 2 x 7 + 1 x 1 6 = 100 m.wt. 100 = c n Its vapour density = —-— =
>
CH3 - CH - CH3
(B)
H *C atom is achiral as all the four valencies are satisfied by four different atoms or groups.
60
^H
-HBr.
Among given compounds only r ^ r
M C1CH2 > C1,CH > C13C 8.
CH,
CH 3
propan-2-ol
CI 16. (c)
NH,
CI
NaNO,^ HCI
'
N 2 cr CI
Cu,Br2 HBr
'
Br
CHEMISTRY TODAY | DECEMBER '05 47
17. ( c ) : Presence o f electron attracting group, (e.g. - N 0 2 , - X, - N R 3 + , - C N , - CHO, - COOH) on the benzene ring increases the acidity of phenol as it enables the ring to draw more electrons from the phenoxy oxygen and thus releasing easily the proton. On the other hand, presence o f electron releasing group (e.g. - CH 3 , - C 2 H 5 , - OCH 3 , - N R 2 ) on the benzene ring decreases the acidity of phenol as it strengthens the negative charge on phenoxy oxygen and thus proton release b e c o m e s difficult. Thus cresols are less acidic than phenol.
OH
OH
OH
OH
Cl
p-nitrophenol
'
/>-chlorophenol-
phenol
W
e
realize that there are several great science a n d m a t h teachers w h o have devotedly s h a p e d
the futures of their students. Their contributions To h o n o u r s u c h d e d i c a t e d m a s t e r s a n d t o s h a r e their techniques for the benefit of other students, we have
CH3 ^-cresol
1 8 . ( a ) : When benzene diazonium chloride solution is warmed, phenol is formed with evolution of nitrogen.
N2C1
Exemplary Chemistry Teacher Award
are barely recognized and appreciated.
($)>(§)>(§)>(§) N0 2
MTG
OH
decided to constitute the
monthly
' M T G Exemplary Chemistry Teacher' award. T h e s t u d e n t s w h o h a v e b e n e f i t e d a r e t h e best s o u r c e o f i n f o r m a t i o n f o r us a b o u t s u c h g r e a t t e a c h e r s . W e invite s t u d e n t s t o p r o p o s e t h e n a m e s o f t e a c h e r s f o r t h e a w a r d by w r i t i n g t o us, g i v i n g t h e f o l l o w i n g information. 1.
19. (c) dilNaOH
20. (a) : H - C - H + H-CH 2 CHO O
Teacher's name a n d career details, contact
IT
-
> C H 2 = CH - CHO A .
> CH,2 t
23. (c) 28. (a) 33. (b) 38. (d) 43. (e) 48. (a) 53. (e) 58. (d) 63. (c) 68. (d) (d) For detailed
number, e-mail,
subject
( P / C / M / B ) , w h e r e d o e s he t e a c h , w h e n d i d
(d) (a) (e) (b) (e) (c) (a) (c) (c) (d)
lie teach you. 3.
4.
25. 30. 35. 40. 45. 50. 55. 60. 65. 70.
(a) (a) (c) (a) (c) (e) (e) (e) (b) (a)
answers, refer to MTG's Kerala P M T Explorer.
CHEMISTRY TODAY | DECEMBER '05 47
h e / s h e uses to e x p a n d
your
thinking... (200 words).
|
(B) 24. (d) 29. (d) 34. (b) 39. (d) 44. (a) 49. (e) 54. (a) 59. (a) 64. (c) 69. (e)
Narrate an incident which demonstrates the techniques
CH - CH - COOH
H30+
22. 27. 32. 37. 42. 47. 52. 57. 62. 67. 72.
2.
address, phone
HCN
(e) (e) (b) (d) (e) (e) (d) (b) (c) (d) (b)
;>
H
1 i—i CH2 - c m - CHO I OH • ~
21. 26. 31. 36. 41. 46. 51. 56. 61. 66. 71.
S t u d e n t ' s n a m e , c l a s s , s c h o o l , city, c o n t a c t address, phone number, e-mail.
H o w d i d he i n f l u e n c e y o u r life. ( 1 0 0 w o r d s )
S e n d y o u r e n t r i e s t o .. M T G L e a r n i n g M e d i a (P) Ltd. 4 0 6 , Taj A p t . R i n g R o a d , New Delhi - 1 10 0 2 9 e-mail :
[email protected] Every m o n t h the s e l e c t e d entry i n c l u d i n g t h e t e a c h e r ' s p r o f i l e w i l l b e p u b l i s h e d in M a t h e m a t i c s Today, C h e m i s t r y Today, Physics For You
and
Biology Today. The teacher will also be a w a r d e d a certificate, Rs. 1 1 0 0 c a s h a n d a l i f e - t i m e s u b s c r i p t i o n o f t h e magazine.
47
Practice Paper for
5 on " 5 2 3 r d a n d 24th< ^ A p r i l 2006,
West Bengal J E E 2006 1. Which of the following reacts with nitrous acid to form an alcohol? (a) CH 3 CH 2 NH 2 (b) (CH 3 ) 2 NH (d) C 2 H 5 X. (c) (CH 3 ) 3 N
9. Which of the following alkyl halides is hydrolysed by S N 1 mechanism? (a) (CH3)2CHC1 (b) CH3CH2C1 (c) CH3CH2CH2C1 (d) (CH3)3CC1.
2.
10. For the reaction
The reaction RCH2CH2COOH
red P / B r ,
ZnCl,
C2H5OH + HX C2H5X > the decreasing order of reactivity of halogen acid is (a) HI > HCI > HBr (b) HI > HBr > HCI (c) HCI > HBr > HI (d) HBr > HI > HCI
RCHX'H - COOH I Br
is called (a) Reimer-Tiemann reaction (b) Hell Volhard Zelinsky reaction (c) Cannizzaro's reaction (d) Howarth's reaction. 3. When propanone is treated with PC15, it forms (a) trichloropropanone (b) hexachloropropanone (c) 2,2-dichloropropane (d) trichloropropanal. 4. (a) (b) (c) (d)
Ketones are less reactive than aldehydes because C — O group is less polar in ketones of electromeric effect of steric hindrance of the attacking reagent none of these.
5. Hexamethylene tetramine is also called (a) benzoin (b) formalin (c) urotropin (d) none of these. 6. When but-3-en-2-ol reacts with aq. HBr, the product formed is (a) 3-bromobutan-l-ene (b) l-bromobut-2-ene (c) a mixture of both (a) and (b) (d) 2-bromobut-2-ene. 7. 1-chlorobutane on reaction with alcoholic potash gives (a) 1-butene (b) 1-butanol (c) 2-butene (d) 2-butanol. 8.
Identify Z in the following series. _
TT H2C — CH 7
(a) C 2 H 5 I (c) CHI3 62
HBr
hydrolysis
> Y-
(b) C 2 H 5 OH (d) CH 3 CHO.
Z
11. (A) (B) (C)
Some statements are given below. Silicon is harder than carbon. Silicon has vacant cf-orbital and carbon has not. Carbon forms readily C - C bond but silicon does not form Si - Si bond. (D) Silicon can displace carbon from Na 2 C0 3 . Among the above, true statement(s) is/are (a) only B (b) only A and D (c) only B, C and D (d) only B and C. 12. Some statements are given below. A. Astatine is unstable. B. Formula of fluorite is CaF3. C. Bond dissociation energy of I2 < F2. D. Fluorine shows +1 oxidation state. Among the above, the incorrect statement is/are (a) only A (b) only B and D (c) only A, B and C (d) all of these. 13. Fluorine is a better oxidising agent than Br2 because of its (a) small size (b) more electron-electron attraction (c) non metallic nature (d) highest electronegativity. 14. Which of the following does not form polyhalide? (b) Br2
(a) Cl2 (c) h
(d)
F2.
15. Pick up incorrect statement regarding HF.
(a) It is used for making chlorofluorocarbons (CF2C12) used as refrigerating agents. CHEMISTRY TODAY | DECEMBER '05 47
(b) It is used for removing silica from graphite. (c) Aqueous HF is used for etching glass. (d) HF is stored in glass bottles. 16. The crystal structure of sodium metal is (a) body centered cubic (b) face centered cubic (c) hexagonal (d) tetragonal. 17. Which of the following is the strongest oxidising agent? (a) silicon (b) phosphorus (c) sulphur (d) chlorine". 18. are (a) (c)
The first ionisation potential of Na, Mg, AI and Si in the order Na < Mg > AI < Si (b) Na > Mg > AI > Si Na < Mg < AI < Si (d) Na > Mg > AI < Si.
19. C 14 isotope in an old wood is one eighth present in fresh wood. If the half life of C 14 is 5580 years, the age of wood in years is given by (a) v ;
2.303
x
log 8
0.693 5580 (c) 5580 log 8
2.303x5580, n log8 ' 0.693 (d) none of these.
v(b)
20. The decay constant of a radioactive sample is X. The half life and mean life of the sample are respectively
(a)
1
• 2
in-
(c) A,ln2, — \
. 21
(b) lnr x
(d) none of these.
21. the (a) (c)
In the reaction: 4 Be 9 + projectile —> 4 Be 8 + 0 n \ projectile is a-particle (b) P-particle positron (d) y-ray.
22. (a) (b) (c) (d)
The instability of a nucleus is due to high proton electron ratio high proton neutron ratio low proton electron ratio low proton neutron ratio.
23. A colloidal state can be purified by (a) filtration (b) peptization (c) sedimentation (d) dialysis. 24. Which one of the following forms mono molecular layer? (a) chemisorption (b) chemical adsorption (c) Langmuir adsorption (d) all of these. C H E M I S T R Y T O D A Y | DECEMBER '05 47
47
25. The substance which gets adsorbed on the surface of a solid is called (a) absorbate (b) adsorbent (c) miscelle (d) catalyst.
26. The salt hydrolysis of the salt of a strong acid and weak base is called (a) anionic hydrolysis (b) cationic hydrolysis (c) amphoteric hydrolysis (d) none of these. 27. Purification of NaCl by passage of HCl gas through brine is based on (a) common ion effect (b) distribution coefficient (c) Le Chatelier's principle (d) displacement law. 28. A mixture of a weak acid (say acetic acid) and its salt with a strong base (say sodium acetate) is a buffer solution. Which other pair of substances from the following may have a similar property? (a) HCl and NaCl (b) NaOH and NaN0 3 (c) KOH and KC1 (d) NH 4 OH and NH4C1. 29. (a) (b) (c) (d)
Solubility product (K,P) varies with temperature does not change with temperature. changes with the change in concentration of ions both (a) and (c).
30. Conjugate base of a strong acid is (a) strong (b) weak (c) neutral (d) none of these. 31. Which of the following is not a Lewis base? (a) NH 3 (b) O2" (c) H 2 0 (d) I+. 32. The pH of the solution containing 10 ml of 0.1 N NaOH and 10 ml of 0.05 N H 2 S0 4 would be (a) zero (b) 1 (c) greater than 7 (d) 7. 33. If 5 ml of M/100 HCl is added to 10 ml of M/100 HCl, the pH of the mixture will be (a) 1 (b) 2 (o) 3 (d) 4. 34. For equimolar solutions pH is more for (a) HCOOH (b) C 6 H s COOH (c) CH 3 COOH (d) melonic acid. 35. Other things being equal, the life of a Daniel cell may be increased by
(a) (b) (c) (d)
keeping temperature low using large copper electrode using large zinc electrode decreasing concentration of Cu 2+ ions.
36. (a) (b) (c)
The electrode potential of an electrode is the potential applied to the electrode the ionisation potential of the material of the electrode the tendency of the electrode to lose or gain electrons when it is in contact with its ions (d) the potential energy of the electrons in an electrode.
37. The difference of potential of two electrodes of a galvanic cell is called (a) potential difference (b) ionic difference (c) EMF (d) electrode difference. 38. The quantity of current required to produce 15 g of zinc in 200 minutes is (a) 2.67 A (b) 3.69 A (c) 1.67 A (d) none of these. 39. The current of 2.6 amperes was passed through CuS0 4 solution for 6 minutes and 20 seconds. The amount of copper deposited is (a) 0.3175 g (b) 0.0031 g (c) 6.35 g (d) 3.175 g. 40. In the electrolysis of the fused salt, the weight of the substance deposited on an electrode will not depend on (a) temperature of the bath (b) current intensity (c) time of electrolysis (d) electrochemical equivalent of ions. 41. A system is changed from state A to state B by one path and from B to A by another path. If AE, and AE2 are the correspondin'g changes in internal energy, then (a) A£, + A£ 2 = +ve (b) A£, + A£ 2 = - v e (c) AE[ + AE2 = 0 (d) none of these. 42. the (a) (c)
When ammonium chloride is dissolved in water, solution becomes cold. The change is endothermic (b) exothermic supercooling (d) none of these.
43. (a) (b) (c) (d)
Enthalpy change of a reaction does not depend upon conditions of a reaction initial and final concentrations physical states of reactants and products reaction path.
64
44. (a) (b) (c) (d)
Select the correct order in the following. 1 erg > 1 joule > 1 cal 1 erg > 1 cal > 1 joule 1 cal > 1 joule > 1 erg 1 joule > 1 cal > 1 erg.
45. (a) (c) (d)
The heat of formation of a compound is always positive (b) is always negative may be positive or negative is zero at any stage of the reaction.
46. Which of the following compounds has an electrovalent linkage? (a) CH 4 (b) MgCl 2 (c) SiCl4 (d) I2. 47. (a) (b) (c) (d)
Indicate the nature of the bonding in CC14 and CaH2? covalent in CC14 and electrovalent in CaH 2 electrovalent in both CC14 and CaH 2 covalent in both CCI4 and CaH 2 electrovalent in CC14 and covalent in CaH 2 .
48. (a) (b) (c) (d)
Choose the incorrect statement. o bond is weaker than n bond TI bond is weaker than c bond 71 bond is present along with aCTbond G bond can be present alone.
49. (a) (b) (c) (d)
Solid NaCl is a bad conductor of electricity because in solid NaCl there are no free ions it is covalent in solid NaCl there is no movement of atoms in solid NaCl there are no electrons.
50. Molten sodium chloride conducts electricity due to the presence of (a) free electrons (b) free ions (c) free molecules (d) atoms of sodium and chlorine. ANSWERS
1. 6. 11. 16. 21. 26. 31. 36. 41. 46.
(a) (c) (c) (c) (d) (b) (d) (c) (c) (b)
2. 7. 12. 17. 22. 27. 32. 37. 42. 47.
(b) (c) (b) (d) (d) (a) (c) (a) (a) (a)
3. 8. 13. 18. 23. 28. 33. 38. 43. 48.
(c) (c) (d) (a) (d) (d) (b) (b) (d) (a)
4. 9. 14. 19. 24. 29. 34. 39. 44. 49.
(c) (d) (d) (b) (d) (a) (c) (a) (c) (c)
5. 10. 15. 20. 25. 30. 35. 40. 45. 50.
(c) (b) (d) (b) (a) (b) (a) (a) (b) (b)
C H E M I S T R Y T O D A Y | DECEMBER '05 47
SOLVED PAPER
MANIPUR PMT - 2005 1. An organic compound Xon treatment with acidified K 2 Cr 2 0 7 gives Y, which when treated with I2 + NaOH gives triiodomethane. The compound X is (a) CH3OH (b) CH3CHO (c) CH 3 CH(OH)CH 3 (d) CH3COCH3. 2. 2-Acetoxybenzoic acid is an (a) antiseptic (b) antibiotic (c) antipyretic (d) antimalarial. 3. (a) (b) (c) (d)
Buna-S is a polymer of butadiene and styrene adipic acid and urea urea and formaldehyde chloroprene.
4. the (a) (c)
The carbohydrate which can't be hydrolysed by human digestive system is starch (b) cellulose glycogen (d) all of these.
5. but (a) (c)
Which of the following bases is found in RNA not in DNA? adenine (b) uracil thymine (d) guanine.
6. Which of the following is an azo dye? (a) methyl orange (b) malachite green (c) indigo (d) alizarin. 7.
At 300 K, the value o f Kc for the reaction
l/2N, + 0
2
^ N 0 2 is 2 x 1 o 4 . What will be the value
of K'c for 2NO z ^ (a)
V2 xlO 2
(c) 2 x 1 0
4
N2 + 2 0 2 ? (b)
1
4x10 s 4 (d) 1 x 10 .
(a) n = 3, / = 0, m = 0 (b) n = 3, / = 1, m = - 1 (c) n = 2, I = 0, m = - 1 (d) n = 2, I = 1, m = 0 10. Which pair of atomic numbers represents s-block elements? (a) 7, 15 (b) 6, 12 (c) 9, 17 (d) 3, 12 11. Which of the following has minimum dipole moment? (a) but-l-ene (b) cis but-2-ene (c) trans but-2-ene (d) 2-methylpropene. 12. For the reaction, C3H8 + 50, w 3CO 2 0.0 + 4 H 2 0 constant temperature is (a) RT (b) -RT (c) 3RT (d) - 3 R T . 13. (a) (b) (c) (d)
(/) ,
AH - AE at
Which of the following is not a redox reaction? 2H 2 + 0 2 2H20 CaC03 CaO + C 0 2 Na + H 2 0 NaOH + 1/2 H, MnCl 3 -H> MnCl 2 + 1/2 Cl 2 .
14. Which of the following anions is the weakest base? (a) C 2 H 5 0" (b) CN" (c) CH3COO(d) NO3-. 15. Ammonia gas can be dried over (a) CaCl 2 (b) conc. H 2 S 0 4 (c> P 2 0 5 (d) CaO. 16. Which of the following leaves no residue on heating? (a) CU(N0 3 ) 2 (b) N a N 0 3
8. The rate of d i f f u s i o n of methane at a given temperature is twice that of X. The molar mass of X in g mol"1 is (a) 64 (b) 32 (c) 40 (d) 80.
17. In which of the following there is no S - S bond? (a) S 2 0 4 2 " (b) S 2 0 3 2 " 2 (c) S,0 6 " (d) S 2 0 7 2 -.
9. Which of the following sets of quantum number is not possible?
18. If a = b / c and a = (3 = y = 90°, the crystal system is
47
(c)
Pb(N03)
2
(d)
NH
4
N0
3
.
C H E M I S T R Y T O D A Y | DECEMBER '05 47
(a) cubic (c) tetragonal
(b) rhombic (d) monoclinic.
ff
OCCH, COOH
19. 18 carat gold contains (a) 18% gold (b) 24% gold (c) 75% gold (d) 60% gold.
2.
20. The number of water molecules present in a drop of water having a volume of 0.05 mL and density of 1.0 g mL"1 is
3. ( a ) : Buna-S rubber is a co-polymer of three moles of butadiene and one mole of styrene. In Buna-S, 'Bu' stands for butadiene, 'na' for sodium (Na) which is polymerizing agent and 'S' stands for styrene.
(a) 6.022 x 1021 22 (c) 6.022 x io
(c):
ACTS a s
a n
anti
pyretic-
2-acetoxybenzoic acid (aspirin)
(b) 1.673 x IO21 22 (d) 1.084 x 10 .
CH =
21. In the nuclear reaction, 4 Be 9 (P, a ) X, X is (a) 2 He 4 (b) 3 Li 6 7 (c) 3Li (d) 4 Be 8 .
CH,
«CH2 = C H - C H = C H 2 + « [ Q 1,3-butadiene
22. The bond order of 0 2 ~ is (a) 0.5 (b) 1.0 (c) 1.5 (d) 2.5
styrene
CH,-CH=CH-CH2-CH-CH2-\
23. Which of the following has the highest boiling point at 1 atm? (a) 0.1 M sucrose (b) 0.1 M NaCl (c) 0.1 M urea (d) 0.1 M BaCl 2 .
gi Buna-S
4. (b) : Cellulose is insoluble in water and in most of the organic solvents.
24. In the reaction X + Y —» Z, keeping [X] constant 5. (b) iffy] is doubled, the rate becomes double and keeping 6. ( a ) : The azo dyes contain one or more azo groups. [K] constant if [X] is doubled, the rate becomes four - N = N - as the chromophore. times. The order of the reaction is (a) 0 (b) 1 H O 3 S < ^ - N = N - ( o ) - N(CH3)2 (c) 2 (d) 3. methyl orange 25. In the following sequence of reactions, CH 3 CH 2 Br
K0H(alc )
Z is (a) CH 2 = CH 2 (c) CH = CH
> X
Y
KOH(ALC
^
7.
(c) :
X
For N 0 2 —
(b) CH 2 BrCH 2 Br (d) CH 3 CH 3 .
acidified K 2 C r 2 0 7
»y
I, + N a O H iodofonn test
acidified K2, C r2, 07,
^ N 2 + 02,
1
Kr<
=
=
2 x io 4
KC]
=
^
R
1
II
00 —2————> CHL
8.
(a):
or,
4=-
4x10 s
(2x10 )
CHI,
> CH 3 C - CH 3
CHEMISTRY TODAY | DECEMBER '05 47
KC
Hence for 2NO, ;—^ N, + 20 2 ,
Iodoform test is exhibited by ethyl alcohol, acetaldehyde, acetone, methyl ketones and those alcohols which possess CH 3 CH(OH) - group. O CH 3 CH(OH)CH 3
N0 2 ;
Z
ANSWERS
1.
1 (b) : - N 2 + 0 2
A4 - = 2
=
Mn
or, 2 = ,
MY
M y2 = 6 4 16 9. (c) : For n = 2, / = 0, 1 For / = 0, m = 0 (only one value). a
10. (d) : In i-block elements, the last electron enters
47
the ns energy shell. The maximum capacity o f ns energy shell is o f t w o electrons, thus these elements have valency shell configuration either ns1 or ns2. 11. (c) : Trans-homers 12. ( d ) : C3H8
S2072" : O - S - O - S - O "
II
II
o
have zero dipole m o m e n t and
are non-polar.
o
o
o
18. (c) : For tetragonal : a = b * c , a = P = y = 9 0 ° , + 502(r)
w
3 C 0 2 ( g ) + 4 H 2 0 (/)
An = 3 - ( 6 ) = - 3 . AH= AE + A nRT AH-AE = - 3 RT. 13. (b) : CaC03
CaO + C 0 2
t w o equal edges, all right angles, five planes and f i v e axes.
18
1 9 . (c) : 18 karat gold means ^ - x 100 = 75%.
This is an e x a m p l e o f decomposition reaction and there
18 karat gold means that 18 parts o f the j e w e l r y is gold
is no c h a n g e in oxidation number. So it is not a redox
and the balance 6 parts is s o m e other metal or equal
reaction.
to about 75 percent gold plus 2 5 percent o f s o m e other
1 4 . ( d ) : A m o n g the given options, H N 0 3 is the strongest acid, s o its conjugate base N 0 3 ~ ion will be weakest base. 1 5 . ( d ) : For drying o f a m m o n i a gas, the c o m m o n dehydrating agents like H 2 S 0 4 or CaCl 2 or P 2 0 5 cannot be used as t h e s e react with N H 3 . H o w e v e r , quick lime, is used as it does not react with N H 3 but reacts readily with moisture. CaO + H , 0 - > C a ( O H ) 2 quick lime 1 6 . ( d ) : Alkali nitrates form nitrites and o x y g e n on
metal alloy. 2 0 . ( b ) : M a s s = v o l u m e x density = 0.05 x
= 0.05 g m 6.023x10"
N o . o f m o l e c u l e s in 0 . 0 5 6e water = = 0 . 0 1 6 7 3 x 10 2 1 . ( b ) : 4Be
9
23
+ ,H'
18
x 0.05
21
= 1.673 x 10 . 3 Li
6
+
2He
4
This is an e x a m p l e o f p, a reaction.
22. (c) : 0 2 " - ( a l J ) 2 ( a * Is) 2 (o2s)2 (a*2s)2 (7t2Py)2 (n2Pz)2 (n*2Py)2 10-7 Bond order = — - —
heating.
i.o
N u m b e r o f m o l e c u l e s in 18 g water = 6 . 0 2 3 x 10 2 3
=
2
2NaN03 -» 2NaN02 + 0 2
(o2px)2 (n*2p.y
3 , c T = 1-5
2
Nitrates o f alkaline earth m e t a l s and heavy metals
2 3 . ( d ) : B o i l i n g point is a c o l l i g a t i v e property w h i c h
d e c o m p o s e to g i v e mixture o f nitrogen dioxide and
depends upon the number o f m o l e c u l e s / i o n s .
o x y g e n a l o n g with a solid residue o f metal oxide. 2Pb(N03),
2PbO + 4 N O , + 0 2
2 C U ( N 0 3 ) 2 - > 2CuO + 4 N 0 2 + 0 2
A m o n g the given options, B a C l 2 has greater number o f ions, i.e. it has highest boiling point.
24. (d) : X + Y
Z
A m m o n i u m nitrate d e c o m p o s e s to form nitrous o x i d e
If K is doubled, rate b e c o m e s double i.e. with respect
gas.
to Y, order o f reaction = 1. NH4N03
17. (d) : S2042" :
_
9
II
N20 + 2H20
I f X is doubled, rate b e c o m e s four times i. e. with respect
0
to X, order o f reaction = 2.
I!
O 2
S,03 ~ :
Overall order o f reaction = 1 + 2 = 3.
O - S - S - O "
H
I
H
I
2 5 . (c) : H - C - C - H + KOH (alc.) H
O - S - O"
Br
>
H
H
I
I
H - C = C - H
O O II II
: o-s-s-cr II II
o o 74
Br CH 2 = CH 2
X
Br
CH,2 — CH,2
+ HBr
w CH=CH
Y
CHEMISTRY TODAY | DECEMBER'0547
Genius RULES AI! students preparing for PMT/PET examinations can participate in W f c t / G " Chem-Genius Contest. Answers marked only on the entry form of the magazine / photocopy of form will be accepted. More than one response to a question will be disqualified. Prizes • 1st Prize-LG Mobile phone • 2nd Prize-Adidas Bag • 3rd Prize - MTG Books (worth Rs. BOO/-) The entries with maximum number of correct answers for three consecutive months (February '08 - April '08) will be awarded 1 st prize. 2nd and 3rd prize will be given to the next maximum scorers. In case of a tie, the winners will be decided through a lucky draw. The decision of the editor will be final and binding in all cases and will not be a matter for consideration of any court and no correspondence will be entertained. Name and photograph of the prize winners of this contest will be published in the June issue of 2008. MTG is not responsible for any postal delays, transit losses or mutilation of entries. Last Date The entries should reach on/before 31st March '08 to - WfcfcGr Chem-Genius Contest-3,406, Taj Apartment, Ring Road, Near Safdarjung Hospital, New Delhi-29. [Note : Enclosures include a passport size photograph and a photocopy of age proof.] r.
TI has how many significant number ? (a) 4 (b) zero (c) 3 (d) an infinite number
2. A 1.0 g projectile is shot from a gun with velocity 100 m/s. What is the de Broglie wavelength ? (a) 3.33 x IO"34 cm (b) 6.63 x 101-34 cm 33 (c) 3.33 x 10" m (d) 6.63 x 10~33 m The third line in the Balmer series corresponds to an electronic transition between which Bohr orbits in hydrogen ? (a) 3 —> 2 (b) 4—>2 (c) 2 -s> 1 (d) 5 2 4. The dipole moment of HBr is 2.60 x IO 3 0 cm, and the interatomic spacing is 1.41 A. What is the percent ionic character of HBr ? (a) 12.9% (b) 11.5% (c) 13.1% (d) 13.9% 5. A litre of milk weighs 1.032 kg. The butter fat it contains to the extent of 4.0% by volume has a density of 865 kg/m 3 . What is the density of the fatfree skimmed milk ? (a) 1080 g/cm 3 (b) 1040 kg/m 3 C H E M I S T R Y T O D A Y | MARCH '08 204
(c)
1080 kg/m 3
(d) 1140 g/cm 3
6. A gaseous compound is composed of 85.7% by mass carbon and 14.3% by mass hydrogen. Its density is 2.28 g/L at 300 K and 1.00 atm pressure. Determine the molecular formula of the compound. (a)
C2H2
(b) C 3 H 4
(C)C4H8
(d)C4H4
7. The density of a 2.0 M solution of acetic acid (MW= 60) in water is 1.02 g/mL. Calculate the mole fraction of acetic acid. (a) 0.0038 (b) 0.0380 (c) 3.80 (d)4.12 A saturated solution of silver benzoate, AgOCOC 6 H 5 , has a pH of 8.63. Ka for benzoic acid is 6.5 x 10 5. Estimate the value of Ksp for silver benzoate. (a) 1.4 x i o ^ 3 (b) 1.4X10- 2 2 (c) 1.96X10" (d) 1.96X10- 3 , The activity of 30 mg of 247 Cm is 2.8 nCi. Calculate the half-life of 247 Cm. (a) 1.5 x 109 years (b) 2.2 x 109 years 7 (c) 1.5 x 10 years (d) 1.9 x 108 years 10.Calculate the partial pressure of carbon monoxide
from the following data: CaCO 3(j) — > CaO (j) + C0 2 1\ Kp = 8 x l(H C0 2 ( f f ) + C w - > 2 C 0 f e ) , A , = 2 (a) 0.2 (b) 0.4 (c) 1.6 (d)4.
(a) K
The orbital diagram in which aufbau principle is violated
w rmmif i w 11
tl
1
t
11 1
(b) Mn
16. 1,3-butadiene has (a) sp (b) sp2
1
1 t 1 (d) 11 11 11 1 '2 Which of the following pairs of compounds are isoelectronic and isostructural ? (a) N0 3 - C0 3 2 " (b) N0J33 - , C103 (c) CO/-, S0 3 (d) N0 3 , S0 3
(c) 11
The oxidation number of sulphur in S8, S2F2 and H2S are (a) 0, +1 and - 2 (b) +2, +1 and - 2 (c) 0, +1 and +2 (d) -2, +1 and - 2 Oxidation state of nitrogen is incorrectly given for Compound Oxidation state (a) [Co(NH3)5Cl]Cl2 -3 (b) NH 2 OH -1 (c) (N 2 H 5 ) 2 S0 4 +2 (d) Mg3N2 -3 The metal that cannot be produced on reduction of its oxide by aluminium is
(c) Cr
(d) Fe
hybridization. (c) sp3
(d) all
17. At absolute zero (a) only para hydrogen exists (b) only ortho hydrogen exists (c) both para and ortho hydrogen exist (d) none of these 18. The nitride ion in lithium nitride is composed of (a) 7 protons +7 electrons (b) 10 protons +7 electrons (c) 7 protons +10 electrons (d) 10 protons +10 electrons 19. Which ion form hydroxide easily soluble in water ? (a) Zn2+ (b) Ba2+ (c) Mg2+ (d) Al3+ 20. Al dissolves in molten NaOH with the formation of H 2 and (a) sodium aluminate (Na3A103) (b) sodium metaaluminate (NaA102) (c) aluminium hydroxide (d) alumina 21. A salt X gives white precipitates with lead acetate solutions insoluble in hot water and nitric acid. The salt X most probably contains
PRIZE W I N N E R S
WfcfcG- Chemgenius Contest-2 I s t Prize
II n d Prize
Sahil Makhija 2-A/14, NIT, Faridabad, Haryana -121 001
Gaurav Singh Near Saraswati Shishu Mandir, Near Nirala Nagar.Rewa, M.P. 486002
r
III r d Prize
Nipun Gupta Rajwada Complex, Dhar, M.P. 454 001
(Other Highly Commendable Contestants) • Ram Krishna Mishra (Sultanpur, U.P.) • Aniket Deb (Kota, Rajasthan) • Monali Sahu (Balasore, Orissa) • Dipti Bisht (Lucknow, U.P.) • Tilottama Turkar (Navi Mumbai)
"Heartiest Congratulations and Best Wishes for bright future to all winners!' Prizes are being sent. CHEMISTRY TODAY I MARCH '083
I
(a) Cl-
(b) Ba2+
(c) S0 4 2 "
(d)C0 3 2 "
Which compound is formed when excess of KCN is added to aqueous solution of copper sulphate? (a) Na 2 C0 3 (b) CaC0 3 (c) MgC0 3 (d) NaHC0 3 The plot of log k versus 1/T of a reaction is linear with a (a) positive slope and zero intercept (b) positive slope and nonzero intercept (c) negative slope and zero intercept (d) negative slope and nonzero intercept. Which oxide of nitrogen is the most stable? (a) 2 N 0 2 f e ) ^ N 2 f e ) + 20 2 ( g ) ; f = 7 . 6 x 1016 mol litre"1 (b) 2N 2 O fe) — 2 N 2 f e ) + 0 2 ( g ) ; K= 5.3 x 1033 mol litre"1 (c) 2N 2 0 5fe) 2N2(?) + 50 2 ( g ) ; K = 1.2 x 10 3 4 m o l l i t r e 1 (D)
2N0
T E )
^N
2 ( G )
+ 02TE);
K= 2.2 x IO30 mol litre"1. The active ingredient in aspirin is acetyl salicylic acid O n
[or
^ r ° "+ + H2O r r[OJ H3O+ c o
+
withX a = 2.75 x IO" . The pHofthe solution obtained by dissolving two aspirin tablets (containing 0.32 g of acetyl salicylic acid in each tablet) in 250 ml of water is (a) 5.20 (b) 4.20 (c) 3.20 (d)7.20. The hydroxide with highest solubility product is (a)
Al(OH)3
(b) CO(OH)2
(c)
Cr(OH)3
(d) F e ( O H ) 3
Of the following reactions, only one is a redox reaction, identify it. (a) Ca(OH)2 + 2HC1 CaCl2 + 2H 2 0 (b) BaCl2 + MgS0 4 - » BaS0 4 + MgCl 2 (c) 2S 2 0 7 2 + 2 H 2 0 - ^ 4 S 0 4 2 - + 4H+ (d) Cu2S + 2FeO
2Cu + 2Fe + S0 2
According to Kohlrausch law, the limiting value of molar conductivity of an electrolyte A2B3 is (a) X \ 3 + +X° b2 _ (b) 2X° A 3 + + 3 A . V "
( d ) 2\°a2+
n
- 3A.V-
>. Actinium disintegration series starts with A and ends 66
32. Distribution of molecules with velocity is represented by the following curve. Velocity corresponding to point A is
O-C-CHJ
9
(c)
31. How many layers are adsorbed in chemical adsorption? (a) One (b) Two (c) Many (d)Zero.
O 11
0-C-CH3 r ^ r c o o H
at Z, A and Z are (a) A = 90Th232, Z = Pb-206 (b) ^ = 9 2 U 2 3 5 ,Z=Pb-207 (c) A = 92U238, Z = Pb-208 (d) A = 8 6 AC 2 2 7 , Z = Bi-209 30. Pick out the corrcct statement. (a) A catalyst speeds up the reaction by increasing the activation energy (b) A catalyst speeds up the reaction by decreasing the activation energy keeping the reaction mechanism the same (c) A catalyst speeds up the reaction by providing an alternate path of lower activation energy (d) A catalyst alters the positions of equilibrium.
CHEMISTRY TOO AY
MARCH '08
JW M «
33. Which of the following electrolytes is least effective in causing flocculation of ferric hydroxide sol? (a) K 3 Fe(CN) 6
(b) K 2 Cr0 4
(c) KBr
(d) K 2 S0 4
34. Which of the following double sulphate is not an alum ? (a)
K 2 S0 4 .A1 2 (S0 4 ) 3 .24H 2 0
(b)
K 2 S0 4 .Cr 2 (S0 4 ) 3 .24H 2 0
(c)
Na 2 S0 4 .Fe 2 (S0 4 ) 3 .24H 2 0
(d)
CuS0 4 .Al 2 (S0 4 ) 3 .24H 2 0
35. The IUPAC name of CH 2 —CH - CH2 - C = C H is (a) Pent-l-en-4-yne
(b) Pent-4-en-l-yne
(c) Pent-2-en-5-yne
(d) Pent-4-en-2-yne
36. Which of the following sets of quantum numbers is not possible ?
n
I
(a) 5
1
0
(c) 5
1
0
2
\
(b) 3
2 1
- 3i
± 2
(d) 3
2
-2
\
Formation of salicylic acid is by reaction (a) Kolbe's electrolytic reaction (b) Perkin reaction (c) Reimer-Tiemann reaction (d) Hoffmann's ammonolysis 38. Consider the general reaction A + B —> C + D. It is exothermic in forward direction. When we double the temperature by 10°C then the value of equilibrium constant will be (a) Halved (b) Doubled (c) Unchanged (d) Trippled
assertion (b) If both asertion and reason are correct, but reason is not the correct explanantion of assertion (c) If assertion is correct, but reason is incorrect (d) If assertion is incorrect, but reason is correct 46. The compound C 5 H I3 N is optically active and reacts with HONO to give C s H n OH. The compound is (a) N-methylbutanamine (b) 2-Aminopentane (c) 1 -Aminopentane (d) N,N'-Dimethylpropanamine 47. The active species which takes part in the sulphonation of benzene is (a) S0 3 + (b) S0 3 (d) S0 2 + (d)HS0 4 " 48. The end product B of the reaction,
39. Which of the following denotes German silver ? (a) Cu + Al + Ni (b) Ni + Zn + Cr (c) Cu + Zn + Ni (d) Cu + Cr + Sn 40. Dry (a) (b) (d) (d)
ice is a KMn0 4 K 2 S0 4 -A1 2 (S0 4 ) 3 -24H 2 0 Solid C0 2 Sodium hexametaphosphate
42. Carbon-carbon bond distance in benzene molecule is (a) 1.397 A (b) 1.54 A (c) 1.30 A (d) 2.397 A 43. Predict the final product B in the sequence of reaction: 6 0 % H , S 0 44
,. '
HgS04
>A" "
NaOH
B
(a) CH3COONa (b) CH 3 COOH (c) CH 3 CHO H I (d) CH 3 - C - CH 2 - CHO OH 44. The fatty acid that shows reducing property is (a) Ethanoic acid (b) Acetic acid (c) Formic acid (d) Oxalic acid 45. Assertion :
. A
ZNCL,
Na Ether
( . ( O X O )
41. Two solutions having pH 1 and 2, both are mixed, then pH will be (a) 1.76 (b) 0.96 (c) 1.26 (d) 1.5
HC=CH
HCHO/HCl
In any ionic solid MX with Schottky defects, the number of positive and negative ions are same. Reason : Equal number of cation and anion vacancies are present (a) If both assertion and reason are correct and reason is the correct explanation of the
(B)
< ^ C H
w
(0)-CH
(1)
< o > CH2 — CH2C1
2
- < @ >
2
-CH
2
^O)
49. Which of the following compounds is formed when excess of benzene reacts with CH2C12 in presence of anhydrous A1C13? -CH2C1
(a)
(b) CI CI (c) (d)
(in years) is
206
U is 4 x 109 yrs, the age of rock
(a) § § f ( 4 x l 0 > g | 64
= 0.25 . If tm for the
(b)
2 3 0 3 a '6 9 3
CHEMISTRY TODAY MARCH '08
(4xl0>gi
[S 2 _ ]h 2 S = 4 X IO - 2 1
(a) 0.65 M (b) 0.45 M
(c) 0.10 M (d) 0.15 M
NaOH can be used to separate
Although aluminium has a high oxidation potential, it resists corrosion because of the formation of a tough, impervious surface coat of (a) A1N (b) A1203 (c) A1(N03)3 (d) A12(C03)3 The correct expression relating molarity (M), molality (m), densityM (d) and molar mass (M) of solute is M (a) Td-MM' ^MM7 (b) ~ ' d + MM' d-MM' d + MM' (c) m = w (d) M M For the concentrated solution of a weak electrolyte AxBy the degree of dissociation is given by (a) a=^Keq!C(x+y) (b) a = ^ K e q C / x + y
„
(c) a= (d)
AT
\Mx+y
x y
y Cx+y~
a^Keq!xyC
In steam distillation of toluene, the pressure of toluene in vapour is (a) Equal to pressure of barometer (b) Less than pressure of barometer (c) Equal to vapour pressure of toluene in simple distillation (d) More than vapour pressure of toluene in simple distillation 0.025 g of starch was added to 10 ml of gold sol when 1 c.c. of 10% NaCl was added to this gold sol no precipitation occurs. What is the gold number of starch?
(a) 0.025
(b) 0.25
(c) 2.5
(d) 25
An amount of solid NH 4 HS is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm pressure. Ammonium hydrogen sulphide decomposes to yield NH 3 and H 2 S gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to 0.84 atm. The equilibrium constant for NH 4 HS decomposition at this temperature is (a) 0.30 (b) 0.18 (c) 0.17 (d)0.11
Least melting point is shown by the compound (a) PbCl 2 (b)SnCl 4 (c) NaCl (d)AlCl 3 Enthalpy change of heterolytic fission of C - CI bond is given as CH 3 - CI ->> CH 3 + CI" CH 3 CH 2 CI
CH 3 CH 2 + c r
(CH 3 ) 2 CHC1 (CH 3 ) 3 CC1
AHx ° AH 2 °
(CH 3 ) 2 CH + CI" Ah 3 ° (CH 3 ) 3 C + + CI-
For the chemical reaction: N 2 ( g ) + 3 H 2 f e ) ; = ^ 2NH 3 f e | at 500°C, the value of
AH°
(a) AH; > AH; > AH; > AH; (b) AH; < AH; < AH; < AH; (c) AH; < AHI < AH; < AH;
KP is 1.44 x 10 -5 , when partial pressure is measured in atmosphere. The corresponding value of KC with concentration mol litre -1 is (a) 1.44 x 10 5 /(0.082 x 500) 2 (b) 1.44 x 10-7(8.314 x 733)~2 (c) 1.44 x 10-5/(0.082 x 773) 2 (d) 1.44 x 10-7(0.082 x 7 7 3 ) 2
(d) AH; > AH; > AH; > AH; 2 is the equilibrium constant for the reaction at a constant temperature. What is the degree of dissociation for A2 or fi2? (a) 0.2
(b) 0.5
W
^
W
]
Highest pH is given by (a) 0.1 M H 2 S0 4 (c) 1 N NaOH
^
For the concentration cell Zn|Zn 2+ (M,)|jZn 2+ (M 2 )|Zn, the value of AG will be negative if (a) Mx = M2 (b) M, > M2 (c) M1 < M2 (d) none of these
Which of the following metals give hydrogen with very dil. HN0 3 ? (a) Al (b) Mg (c) Au (d) Sn
What is the pH of the mixture 100 ml IN HCI + 60 ml IN NaOH ? (a) 0.50 (b) 0.40 (c) 0.60 (d) 0.20
Inert pair effect is predominant in (a) Si (b) Pb (c) Ge
0.4 gm of an organic compound gave 0.188 g of silver bromide by a halogen estimation method. The percentage of bromine in the compound is (atomic mass o f A g = 108, Br = 80) (a) 39.8% (b) 46.0% (c) 20.0% (d) 40.0%
The percentage ionic character of a bond having 1.275 A its length and 1.03 D its dipole moment is (a) 10% (b) 15% (c) 16.83% (d) 18.8% Which species has the maximum number of lone pair of electrons on the central atom ? (a) CIO3- (b) XeF 4 (c) SF4 (d) [I3]"
The ozonolysis of (CH 3 ) 2 C = C(CH 3 ) 2 followed by treatment with zinc and water will give (a) acetone (b) acetaldehyde and acetone (c) acetic acid (d) formaldehyde
Measurement of the amount of dry gas collected over water from volume of moist gas is based on (a) Gay Lussac's law (b) Dalton's law of partial pressure (c) Boyle's law (d) Avogadro's hypothesis
( a ) K p = e-«™r (c) Kp — R1VAAG°
( b
)^=z|p! K RT
(d) AG = e' "'
(d) Sn
Which of the following is not a protonic acid? (a) B(OH) 3 (b) PO(OH) 3 (c) SO(OH) 2 (d) S0 2 (0H) 2
In P4Oio molecule the number of oxygen attached to each phosphorus atom is (a) 2 (b)3 (c)4 (d)5
The standard free energy change AG° is related to equilibrium constant KP as
(b) 0.1 M NaOH (d) 1 N HCI
Which of the following resonating structure of 1-methoxy-l, 3-butadiene is least stable ? (a) CH 2 - CH = CH— O - CH 3 •
(b) CH 2 - C H = C H = 0 - C H 3 (c) CH 2 - CH = C H = 0 - CH 3 (d) CH 2 - CH = CH = 0 - CH 3 CHEMISTRY TODAY | MARCH'08209
PAN stands for (a) CH 2 = O (b) CH 2 = CH CH = O (c) CH,COONO, (d) C H 3 C H 2 0 - N = 0 II O Allyl isocyanide has (a) 9 sigma and 4 pi bonds (b) 8 sigma and 5 pi bonds (c) 8 sigma, 3 pi and 4 non-bonded electrons (d) 9 sigma, 3 pi and 2 non-bonded electrons Intermolecular hydrogen bonding is strongest in (a) methylamine (c) formaldehyde
(b) phenol (d) methanol
Which of the following compounds has isopropyl group ? (a) 2,2,3,3-tetramethylpentane (b) 2,2-dimethylpentane (c) 2,2,3-trimethylpentane (d) 2-methylpentane C 7 H 8 0 shows how many isomers? (a) 2 (b)3 (c)4
(d) 5
The most stable conformation of 1,2-diphenylethane is
The hydrocarbon is (a) cyclohexane (c) cyclohexene
(b) cyclohexyne (d) cyclobutane
Which of the following does not have chirai centre? CH,
OH
(a)
HO
COOH
HOOC
OH
(b) CH,
( c )
X
= \
(d)
CH 2 OH
Br CH 2 CH 3
The correct order of basicities of the following compounds is ,NH
CH3-CH2-NH2
CH3-C^ (1)
N H
(2) o
2
(CH 3 ) 2 NH
CH3-C-NH2
(3)
"
(a) 2 > 1 > 3 > 4 (c) 3 > 1 > 2 > 4
(4)
(b) 1 > 3 > 2 > (d) 1 > 2 > 3 >
4 4
Diabetes is detected by testing urine of the patient with (a) Tollen's reagent (b) Nessler's reagent (c) Fenton's reagent (d) Benedict's solution Oxidation of glucose is one of the most important reactions in a living cell. What is the number of ATP molecules generated in cells from one molecule of glucose? (a) 36 (b) 12 (c) 38 (d) 28 Match List I with List II and select the correct answer from the given codes. List I
c6H5 Arrange the following nucleophiles in the order of their nucleophilic strength (a) OH" > CH3COO- > OCH3- > C 6 H 5 0 " (b) C H J C O O " < C 6 H S O - < CH3O- < O H " (c) C 6 H 5 0 - < C H J C O O " < C H 3 O - < O H (d) C H J C O O - < C 6 H 5 0 " < O H - < CH3O-
A hydrocarbon of formula C 6 H 1 0 absorbs only one molecule of H 2 upon catalytic hydrogenation. Upon ozonolysis, the hydrocarbon yields a compound of the following structure, H
I
o=c 66
List I I
(a) First amino synthesised in lab
acid
(b) Sulphur containing amino (ii) Cysteine acids (c) Amino acids of highest iso- (iii) Methionine electric point (d) Optically inactive acid a b e d (a) (i) (ii) (iii) (iv) (c) (iii) (ii) (iv) (i) The monomer of dacron
amino
II
CHEMISTRY TOO AY
MARCH '08
(iv)Arginine
a b e d (b) (iii) (ii) (iv) (i) (d) (iv) (iii) (ii) (i) is/are : COOH
O - C H 2 - C H 2 - CH 2 - C H 2 - C - H
(i) Glycine
(a) HOCH 2 - CH 2 OH and
COOH
_ moles of C 2 H 6 0 2 " moles of C 2 H 6 0 2 + moles of H 2 0
O
Xglyco1
(b). (c) HOCH 2 - CH 2 OH and HOOC«
•COOH
(d) F 2 C = C F 2 49. In the sequence of reaction A—-—>5 — > C — ^ — ^ D k3 > k2 > kt, then the rate determining step of the reaction is (a) A B (b) B C (c (d )A-^D 50. Which is not a disproportionation reaction?
0.322 mol = 0.068 0.322 mol + 4.444 mol 4.444 mol : 0.932 Similarly, x. 0.322 mol + 4.444 mol Mole fraction of water can also be calculated as 1 - 0.068 = 0.932 2 2 4 A Al 3. ( d ) : ; root word is cyclohex, suffix is ane and prefix is l-cyclopropyl-4-f-butyl. Therefore IUPACnameis l-cyclopropyl-4-/-butylcyclohexane.
(a)
4. (c) CHO | + OH (b) COOH
CH 2 OH COO" > | + | COOCOO"
(c) NaH + H 2 0 NaOH + H 2 (d) 3CIO (aq) C10 3 (aq) + 2C1 -( ,
5. (a) The first emission line in the atomic spectrum of hydrogen in the Balmer series will appear at ^
cm 1 . This can be calculated as
For Balmer series nl-2,
v (for first line) = ^ Q r - ^ " )
SOLUTIONS
-(B)
1. (c) : Volume of the unit cell = (288 pm) 3 = (288 x IO 1 2 m) = (288 x 10
10
cm) 3
= 2.39 x 10"23 cm 3 Volume of 208 g of the element mass_ = 2 0 8 g - 2 8 . 8 8 cm 3 density 7 . 2 g e m - 3 Number of unit cells in this volume =
=
28.88 cm 3
2.39 xlO" 2 3 cm 3 /unitcell = 12.08 x 1023 unit cells Since each bcc cubic unit cell contains 2 atoms, therefore, the total number of atoms in 208 g
6. (c) • The energy required to remove the first electron is called binding energy of the atom which is given as 24.6 eV. When the first electron is removed, the remaining atom is a hydrogen like atom. Binding energy of such a hydrogen like atom = Z2x 13.6 eV = 2 2 x 13.6 eV = 54.4 eV. So energy required to remove both the electrons is 24.6 eV + 54.4 eV = 79 eV. CH2CH3 7- ( d ) :
= 2 (atoms / unit cell) x 12.08 x io 23 unit cells = 24.16 x io 23 atoms 2. (c): Assume that we have 100 g of solution (one can start with any amount of solution because the results obtained will be the same). Solution will contain 20 g of ethylene glycol and 80 g of water. Molar mass of C 2 H 6 0 2 = 12 x 2 + 1 x 6 + 16 x 2 = 62 g mol"1 20 g : 0.322 mol Moles of C 2 H 6 0 2 = 62 g mol Moles of water = — — - = 4.444 mol 18 gmol
n2 = 3, 4, 5
( O ) Ethyl benzene
C 6 H 5 CH = CHCOOH Cinnamic acid
C 6 H 5 CHOHCH 3
> C 6 H 5 CH — CH2 + c o 2
1-phenylethanol
8. (a) ; 238 U is disintegrated to form the end product 206p b
At present the ratio Pb = 0 2 5 U 1 Initially the no. of a _ U-238atoms present (a - x) No. of U-238 atoms at present
1 + 0.25 1
CHEMISTRY TODAY | MARCH '08 211
For first order reaction(decay of U-238 obeys first order kinetics) , = 2303! a a t (a-x) 0.693 4xl09 1.25 = LOO
a n d *
2.303 , t
=
S
=
M23 TU2
a
2.303 , A „ l n 9 M 5 = < = O693(4Xl0)1°g4
2 x l r
; ' = 0.5M 4x10 I
Maximum possible concentration in solution of Ni 2+ would be 0.5 M. This value is not given in question. The highest possible value of [Ni2+] = 0.45 M as 0.65 M can not be permissible as ionic product then would exceed solubility product of NiS. 10. (c): As 2 S 3 dissolves in NaOH whereas CuS does not. Similarly Al(OH) 3 dissolves in NaOH but Cr(OH) 3 does not. Both (a) and (b) can be separated by NaOH. As 2 S 3 + 6NaOH Na 3 As0 3 + NaAsS 3 + 3 H 2 0 sod. arsenite sod. thioarsenite Al(OH) 3 + NaOH H> Na[Al(OH) 4 ] or NaA10 2 + 2 H 2 0 11. (b) Al is easily oxidised to aluminium oxide as it has high oxidation potential. This coating of A1 2 0 3 resists further oxidation of Al. Molarity = (M), molality = (m), density = (d in kg/lit), volume - ( F i n lit.), mass of solvent = (fFkg), wt. of solute = w kg, molar mass = ( M in kg) ~ W V w m=
Ww
_ w ~ M'V(d-MM')
The value of M i s put into eq. (iv) from eq. (i) M m d-MM' 68
CHEMISTRY TODAY | MARCH '08
(1 - a ) = 1
xxxax+*y>'Cx +y K eq K„„
xx
I x+y
yyCx+y
Patm — Ptoluene
Pll20(g)
P1 toluene < 1Patm
15. ( d ) : Gold number is defined as the amount of milligram of protective colloid added to 10 ml gold sol so that its coagulation is just prevented by adding 1 ml of 10% NaCl solution. Gold number of starch = 0.025 x 103 mg = 25 16. ( b ) : SnCl 4 has more covalent character as the polarisation of CI ions would be large by Sn 4+ ion as the cation has high charge. Evidently m.p. of SnCl 4 is lowest. 17. ( a ) : 3° carbonium ion is most stable whereas CH 3 + is least stable (high energy). =
A^products
-^AHreactants
.'.AH° is largest and AH4° is least. AH x ° > AH2° > A# 3 ° > A# 4 ° 18. ( c ) : A 2 + B 2 ^ = ^ 2 A B (1 - a ) (1 - a ) 2a
(i) ....
(iii)
From equations (ii) and (iii) w fn = M (Vd-MM'V) m
1
The order would be
W (Wt. of solvent) = Wt. of solution - Wt. of solute W- (Vd— MMV)
a «
14. ( b ) : In steam distillation the atmospheric pressure would be equal to the sum of the vapour pressures of toluene and water vapour.
2 x IO 21 = [Ni2+] x 4 x 10"21
M
yaC
X1 yyCx+y~1
2
KsiKNiS) = [Ni ][S -] [Ni2+] =
x+y
a=
9. ( b ) : In a saturated solution of NiS
xaC
(xaC)' (yaCy (1 - a)C
KeqC =
.
2+
(1 - Zn 2+ (M t )
0.5 +p+p
20. (c): When 100 ml 1 N HCl and 60 ml IN NaOH were mixed the resulting normality of acidic solution. N' = N'--
2p = 0.84 - 0.5 = 0.34 orp = 0.17 atm ^(H 2 S) = 0.17 atm, /?(NH3) = 0.5 + 0.17 = 0.67 Kp = /?(NH3) x /7(H2S) = 0.67 x 0.17 = 0.11 atm
I^acid^acid-I^base^base Final Volume 1 x 1 0 0 - 1 x 6 0 _ 40 160 160
= 0.84 atm
Ang = 2 — (1 + 3) = —2 Kp= 1.44 x 10"5;
'
or
1
A.-
Kp = Kr.(RT)A"g 1.44 xlO" 5
Kp (RT)A"g
(0.082 X773)"2 5
= 1.44 x 10" /(0.082 x 773) -2 pH = - l o g ^ - = + log4 = 0.6020 29. (b)
It is most basic. 30. (b) 31. (a) Mass of halogen in 0.4 g of compound 80 xO.188 = 0.08 g 188
21. ( c ) :
% of B r = ^ x l 0 0 0.4 33. (a)
=20%
(1)0, (CH3)2C=C(CH3)2-Zn>H20. (CH 3 ) 2 CO + (CH 3 ) 2 CO
Each P atom is linked with 4 oxygen atoms. = 4.8 x IO-10 e.s.u. x 1.275 x 10' 8 cm = 6.12 x 10~18 e.s.u. cm = 6.12 D % Ionic character _
Observed dipole moment xlOO Dipole moment for complete ionic character
39. (d)
_ 1.03 X100 = 16.83% 6.12 23.(d) : I 3 electrons.
has maximum
number of unpaired F.VFT":
-xe:;
A-
(a) F ,F
(b)
I
CH3COOH > C6H5OH > H20 > CH3OH
-IH
24. (b)
Conformer(d) is staggered form which is most stable because in staggered form the phenyl group are far apart as possible causing minimum repulsion. Structure (a) is skewed and (b) and (c) are eclipsed forms. Weaker the acid stronger will be its conjugate base, hence higher will be the nucleophilicity.
.
• S : F (c)
The octets of all atoms in structures of options (a) and (b) are complete. In structure of option (d) electron deficiency of positively charged carbon is duly compensated by lone pair of electrons of adjacent oxygen atoms. Such deficiency is not compensated in structure of option (c). Peroxyacyl nitrate 37. (d) 38. (d) OH OH OH CH 2 OH OCH 3
Decreasing acidic strength L
So, C H 3 C O O < C 6 H S O - < O H - < C H 3 0 (conjugate base) Increasing basic strength or nucleophilicity.
I (d)
25. (a)
26. ( d ) : NH 4 HS, Initial pressure 0 Pressure at equilibrium 0
:
NH 3 ( g ) + H 2 S fe) 0.5 0 0.5 +p P
Since it absorbs only one H 2 molecule, so it must have one double bond. Further, the product of ozonolysis contains six-carbon atoms, hence it must be cyclohexene. CHEMISTRY TODAY | MARCH'08213
H,
>NH
Reduction
cyclohexene
CH,C:
cyclohexane
O ZnO
^ HCCH2CH2CH2CH2CH
43. (c) : .OH
HO COOH \ * * / / ,CH—HC. OH HOOC
CH, y C H - Br CH^CH^
Contains chirai carbon
CH3 - CH = CHCH 2 OH does not have chirai carbon atom. 44. (b) : In case of CH,C
, lone pair electrons X
NH2 of both the N are readily available which results in higher density of electrons on the central Catom, 2°amine is stronger than 1° amine. Whereas acetamide is least basic because its lone pair is in conjugation of double bond undergo in resonance. Hence the correct order
"NH,
O • (CH3)2 NH > CH 3 CH 2 NH 2 > CH 3 CNH 2
(1) (3) (2) (4) 45. (d) : Urine of diabetic person contains glucose which is reduced by Benedict's solution as glucose is reducing sugar. 46. (c): C 6 H 12 0 6 + 60 2 +6H 2 0->6C0 2 +12H 2 0+ 38 ATP 47. (b) 48. (c): Terylene or dacron is a condensation polymer of ethylene glycol and terephthalic acid. COOH CH 0 - CHN
I OH
I OH
+n
«H 2 0 COOH
— O-CH2CH2-O
C
O O 49. (a): Slowest step is the rate determining step. 50. (c) : In the reaction NaH + H 2 0 h> NaOH + H2 +1-1
+1-2
+1 - 2 + 1
0
H atom undergoes oxidation only. Thus this is not a disproportionation reaction because in disproportionation reaction same substance undergoes oxidation and reduction simultaneously, which is shown in all other options. •
* Based on latest pattern of AIEEE/I IT and PMT's"' The book is represented in such a way that each student would be able to solve any problem of Engineering as well as Medical Entrance E x a m * Book covers complete syllabus in the form of concise t e x t * Improve your problem solving skills with CHECK YOUR CONCEPT boxes • Presentation makes Organic Chemistry interesting and easy® MCQ's of 3 different levels - Concept based, standard, numerical based with detailed solutions* A number of objective and subjective problems to enhance problem solving approach.
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B O O K S
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Model Test Paper
West Bengal JEE 2008 The pattern and the syllabus for WB JEE 2008 has been changed. Under the new pattern 8 0 % questions will be multiple choice questions of 1 mark each. 20% questions (short answer type) will carry 2 marks each. Time: 1 hour
INSTRUCTIONS Question paper consists of two sections: Section A contains multiple choice questions. Each question carries 1 mark. Section B contains short answer type questions. Each question carries 2 marks. SECTION - A
1 In Haber process, 30 litres of dihydrogen and 30 litres of dinitrogen were taken for reaction which yields only 50% of the expected product. What will be the composition of the gaseous mixture under the aforesaid condition in the end? (a) 20 litres NH 3 , 25 litres N 2 , 20 litres H 2 (b) 10 litres NH 3 , 25 litres N 2 , 15 litres H 2 (c) 20 litres NH 3 , 10 litres N2, 30 litres H 2 (d) 20 litres NH 3 , 25 litres N 2 , 15 litres H2. 2. 4 g of copper was dissolved in concentrated nitric acid. The copper nitrate on strong heating gave 5 g of its oxide. The equivalent weight of copper is (a) 23 (b) 32 (c) 12 (d) 20. 3. In hydrogen atom, energy of the first excited state is - 3.4 eV. Then find out the kinetic energy of the same orbit of H-atom. (a) + 3.4 eV (b) + 6.8 eV (c) -13.6 eV (d) +13.6 eV. 4 Mass of ^ Li is 7.016005 amu. Mass of proton is 1.007277 amu and mass of neutron is 1.008665 amu. Mass defect of lithium nucleus in amu is (a) 0.04048 amu (b) 0.04050 amu (c) 0.04052 amu (d) 0.04055 amu 5 Consider the following nuclear reactions 238 9 2 MThe number of neutrons in the element L is (a) 142 (b) 144 (c) 140 (d) 146 6 The statement that is not true for the long form of the periodic table is (a) it reflects the sequence of filling the electrons in the order of sub-energy levels s,p, d and f . (b) it helps to predict the stable valency states of the
Max. Marks: 50
elements (c) it reflects trends in physical and chemcial properties of the elements (d) it helps to predict the relative ionicity of the bond between any two elements. 7. One mole of magnesium in the vapour state absorbed 1200 kJ of energy. If the first and second ionization enthalpies of magnesium are 750 and 1450 kJ mol -1 respectively, the final composition of the mixture is (a) 69% Mg+, 31% Mg2+ (b) 59% Mg+, 41% Mg2+ (c) 49% Mg + , 51% Mg2+ (d) 29% Mg + , 71% Mg2+. 8. The dipole moment of HBr is 0.78 x IO 18 esu cm and inter atomic spacing is 1.41 A . The % ionic character .of HBr is (a) 7-5 (b) 11-7 (c) 15 (d) 27. 9. In P0 4 3 - , the formal charge on each oxygen atom and the P - O bond order respectively are (a) - 0 . 7 5 , 0 . 6 (b) - 0.75, 1.0 (c) - 0 . 7 5 , 1.25 (d) —3.1,1.25 10.Which of the following has maximum root mean square velocity at the same temperature? (a) S0 2 (b) C0 2 (c) 0 2 (d) H2. 11.At constant volume and temperature conditions, the rates of diffusion DA and DB of gases A and B having densities pA and p^ are related by the expression
(a) Da
.PA
= D1
(b)
DA
= D„
PB.
f
/
(c)
DB
PA.
V PB® J
(d)
d
a
=
Db
PA.
P*
\" 2
PA
2.Which expression is correct for the work done in adiabatic reversible expansion of an ideal gas?
CHEMISTRY TODAY | MARCH '08
215
(a)
nRT
In
(b) C^T 2 -T,)
V2/VL
2
(c)
(d)
PAV
I PdV
13. The following equilibria are given N, + 3H, ^ 2NH 3 , KX N, + O,
^F
2NO,
K2
H 2 + V4 0 2 H 2 0 , K3 The equilibrium constant of the reaction 2 NH, + — O2 v2NO + 3 H , 0 in terms of KX, K2 and K3 is (a)
KXK2K3
(b)
(c)
K,K3VK2
(d)
KXK2IK3 K2K3VK}.
14. Vapour density of PC15 is 10416 but when heated at 230°C its vapour density is reduced to 62. The degree of dissociation of PC15 at this temperature will be (a) 6-8% (b) 68% (c) 46% (d) 64% 15. The decomposition of N 2 0 4 to N 0 2 is carried out at 280°C in chloroform. When equilibrium is reached 0.2 mol of N 2 0 4 and 2 x l O 3 mol o f N 0 2 are present in 2 litre solution. The equilibrium constant for the reaction. N204 2 N 0 2 is (a) 1 x 10"3 (b) 2 x 10 3 5 (c) 1 x IO" (d) 2 x IO 5 16. The velocity of a reaction is doubled for every 10°C rise in temperature. If the temperature is raised by 50°C the reaction velocity increases by about (a) 12 times (b) 16 times (c) 32 times (d) 50 times. 17. A G.M. counter is used to study the radioactive process. In the absence of radioactive substance A, it counts 3 disintegration per second (dps). Initially in the presence of A, it records 23 dps and after 10 minutes 13 dps, (i) What does it count after 20 minutes? (ii) What is half-life of A? (a) 8 dps, 10 min (b) 5 dps, 10 min (c) 5 dps, 20 min (d) 5 dps, 5 min. 18. The rate of reaction CljC.CHO + NO —> CHCI3 + NO + CO is given by equation, Rate = &[Cl3C.CHO] [NO]. If concentration is expressed in moles/litre, the units of k are (a) litre2 mole -2 sec 1 (b) mole litre -1 sec -1 1 1 (c) litre m o l e s e c (d) sec -1 .
19. If three Faradays of electricity is passed through the solutions of AgN0 3 , CuS0 4 and AUC13, the molar ratio of the cations deposited at the cathodes will be (a) 1 : 1 : 1 (b) 1 : 2 : 3 (c) 3 : 2 : 1 (d) 6 : 3 : 2. 20. Arsenic sulphide is a negative sol. The reagent with least precipitating power is (a) AICI3 (b) NaCl (c) CaF 2 (d) Glucose 21.2Hg H g ^ , E° = +0.855 V Hg Hg 2+ , E° = +0.799 V Equilibrium constant for the reaction Hg + Hg 2+ - > Hg 2 2+ at 27°C is (a) 89 (b) 82.3 (c) 79 (d) none of these. 22. The precipitate of CaF 2 (Ksp = 1.7 x 10 10) is obtained when equal volumes of the following are mixed (a) 1 0 - M C a 2 + + l O ^ M F (b) 1 0 - 2 M C a 2 + + IO-3 M F " (c) 10"5 M Ca 2+ + 10"3 M F" (d) 10~3 M Ca 2+ + 10~5 M F~. 23. A certain buffer solution contains equal concentration o f X " and EX. The KA for HAT is 10~8. The pH of the buffer is (a) 5 (c) 6
(b) 8 (d) 14.
24. Consider the following reaction, 5 H 2 0 2 + xC\02 + 2 0 H xCl" + >>02 + 6 H 2 0 The reaction is balanced if (a) x=5,y = 2 (b)x = 2,y=5 (c) x = 4,y = 10 (d) x= 5,y~ 5. 25. In the following reaction sequence, c
H 6
B r 5
CuCN/pyridine ^ ^ 523 K
the producty is (a) benzonitrile (c) benzoic acid
dil. H , S Q 4 ? bo
ii
(b) benzene (d) benzamide.
26. Which one of the following amines gives carbylamine reaction? (a) CH 3 CH 2 NHCH 3 (b) C 6 H 5 N(CH 3 ) 2 (c) (CH 3 ) 2 CHNH 2 (d) (CH 3 ) 3 N. 27. Which of the following carbocations is expected to be most stable? NO, NO, (a)
CHEMISTRY TODAY | MARCH '08
216
tertiary butyl alcohol by heating with 20% H 2 S0 4 at 363 K if the yield of the reaction is 65%? (a) 12.8 g (b) 18.2 g
NO.
NO,
(d) I
(c) 21.8 g
28. Equivalent mass of oxidising agent in the reaction, S0 2 + 2H2S 3S + 2H2G is (a) 32 (b) 64 (c) 16 (d) 8. 29. The acid which gives phosphine on heating is (a) H3PO4 (b) HPO3 (c) H 4 P 2 0 7 (d) H3PO3 pn-pn
correct order of increasing boiling point is H2S, H 2 0, H2Te, H 2 Se H 2 0, H2S, H2Se, H2Te H2Te, H2Se, H2S, H 2 0 H2S, H 2 Se, H2Te, H 2 0.
O Y
x
(d) OH
38. The IUPAC name of CH 3 COCH(CH 3 ) 2 is (a) 3-methyl-2-butanone (b) Isopropyl methyl ketone (c) 2-methyl-3-butanone (d) 4-methyl isopropyl ketone 39. Cyclohexene reacts with cold dilute alkaline KMn0 4 to yield (a) cis-1,2-cyclohexanediol (b) trans-1,2-cyclohexanediol (c) cyclohexanone (d) hexane-l,6-dial
A-
SECTION
o
(a) C w " )
(b) |l
(c)
(d)
(a)
0
° 7— CH =
NOH
O
(c)
(d) O O
O
o
35. l-butyne can be converted into 1-bromo-l-butene by reacting it with which of the following reagent? (a) HBr (b) HBr and (C6H5COO)2 (c) Br2 and H 2 0 2 (d) Br2 and CC14. 36. What mass of isobutylene is obtained from 37 g of CHEMISTRY TODAY | MARCH '08
B
41. (a) A sample of U-238 (half-life = 4.5 109 Y) ore is found to contain 23.8 g of U-238 and 20.6 g of Pb-206. Calculate the age of the ore. (b) OF2 is called as oxygen di-fluoride and not written as F 2 0, where as C120 is called as chlorine oxide and not written as OCl2, explain. (c) The dipole-moment of HF is 2 debye. The H F bond length is 0.92 . Calculate the % of ionic character in this compound.
34. Tautomerism is not exhibited by
O
(b)
O
40. To obtain iodine, sea weeds are dried, burnt and extracted with hot water. The mother liquor left after the crystallization of certain salts is treated with (a) chloride (b) conc. H 2 S0 4 (c) conc. NaOH (d) Mn0 2 + conc. H 2 S0 4
33. The most stable carbocation is
/
(a)
OH
32. Which reaction is not feasible ? (a) 2KI + Br2 —> 2KBr +1 2 (b) 2KBr +1 2 —» 2KI + Br2 (c) 2KBr + Cl2 —> 2KC1 + Br2 (d) 2H 2 0 + 2F2 - » 4HF + 0 2
(b)
37. Which of the following will be most readily dehydrated in acidic conditions ? OH OH 0
(c)
30. Which of the following molecules show bonding? (a) P 4 (b)As 4 (c) Sb4 (d) N 2 . 31. The (a) (b) (c) (d)
(d) 28.1 g.
42. (a) 0.296 gm of a bivalent metal was deposited by the passage of 0.5 A current for 30 minutes through a solution of metal sulphate. Calculate atomic mass of the metal. (b) The half-life period of a first order reaction is 30 minutes. Calculate the specific reaction rate of the reaction. What fraction of the reactant remains after 70 minutes? (c) Find equivalent mass of MnO^ - in the following disproportionation reactions: 3MnO^~ + 4H + - > M n 0 2 + 2Mn04 + 2 H 2 0
43. (a) Explain, why a glowing splinter burns vigorously in N 2 0 than in oxygen? (b) Why concentrated H 2 S0 4 or P 2 0 5 can't be used for drying NH3 gas? (c) Explain why brown solution of FeCl3 gets decolourised when H2S gas is passed through it? 44. (a) Which hydracid of halogen is most reactive towards ethanol? (HCI, HBr, HI) (b) A compound C 3 H 8 0 is inert to sodium and when heated with excess HI yields a mixture of methyl iodide and ethyl iodide. What is the structure and name of the compound? (c) Identify A, B, C, D in the following reactions:— C 2 H 5 OH
PCL
A
AgN0 2
B
Sn/HCI
> c
HNO,
D
™N + 2? He + 2+?P Number of neutrons in L = 230 - 86 = 144. 230 L
6. (b) : It does not help to predict the stable valency states of the elements. 7. (a) :Mgfe)+ IE, H> Mg+fe) + e"; IE, = 750 kJ mol"1 Mg+fe) + IE2 Mg2+fe) + O2 -1 +4 Reduction : C10 2 Cl ...(ii) To balance O.N. in Eqn. (i) add 2e~ to R.H.S. we have H202-H> 0 2 + 2e~ ...(iii) To balance charge add 2 0 H to the L.H.S., we have H 2 0 2 + 20H~ —> 0 2 + 2e~ ^
-5
1
• = 10'
Temperature range
Change in velocity of reaction 0-10° 2 times 10°-20° 2 2 times 20° - 30° 2 3 times 30° - 40° 2 4 times 40° - 50° 2 s times Therefore for 50° rise in temperature velocity increases by 2 5 = 32 times.
To balance H and O atoms add 2H 2 0 to the R.H.S., we have H202 +20H" 0 2 + 2 H 2 0 + 2e~ (v)
17. (b) In the absence of A, it counts 3 dps (zero-error). Therefore at the start = 23 - 3 = 20 after 10 min = 13 - 3 = 10 dps after 20 min = 5 dps (recorded = 8 dps) (50% fall in 10 min, Tso = 10 min). 1S. < c
This is the oxidation half equation. To balance O.N. in Eqn. (ii) add 5 e to L.H.S., we have C10 2 + 5 er Cl" ...(vi) To balance charge, add 4 OH" to the R.H.S., we have C10 2 + 5 e" ^ Cl- + 4 OH" ...(vii) To balance O and H atoms, add 2H z O to L.H.S., we have C10 2 + 2 H 2 0 + 5 e" Cl" + 40H" ...(viii) This is the balanced reduction half equation. To cancel the number of electrons lost in Eqn. (v) and gained in Eqn. (viii) multiply Eqn. (v) by 5 and Eqn. (viii) by 2 and add, we have H 2 0 2 + 2 OH"-> 0 2 + 2H 2 0 + 2e-] x 5 ClOo + 2H 2 Q + 5e~ -» C P + 4QH~] x 2
A s r = At[C1 3 CCHO] [ N O ] k = r/[Cl3CCHO] [NO] 1 „-l
. mole litre sec" = mol""1 litre1 sec"-l mole 2 litre -2 + 19. (d) Ag + e Ag, Cu 2+ + 2 e - > Cu, 3+ Au + 3e Au. 3F will deposit 3 moles of Ag, 3/2 moles of Cu and 1 mole of Au. Mole ratio = 3 : 3 / 2 : 1 = 6 : 3 : 2 . Glucose does not give cations to precipitate or coagulate negative As 2 S 3 sol.
5 H 2 0 2 + 2C10 2 + 2 0 H "
E° for the given reaction = 0.855-0.799 = 0.056 V cell =
^
E t
, „ 0.056x2 , 0 „ 0 „ \ogK = = 1.8983 0.059 Kc = antilog 1.8983 = 79.12 ~ 79. or,
22. (b) For CaF 2 , Ksp = [Ca2+][F~]2 Precipitate forms only when ionic product exceeds the solubility product which is possible when [Ca++] = IO 2 M and [ F ] = 10 3 M in that case Kip = 10~2 x ( I0 3 ) 2 = 10 8 i.e Kip>Ksp 23. (b): For acidic buffer
•: [Salt] = [Acid] pH = pKa = - log Ka = - loglO"8 = 8. 76
CHEMISTRY TODAY MARCH '08
2CF + 502 + 6H20
Thus x, the coefficient of C10 2 is 2 while y, the coefficient of Cl" is 5. 25.
( 0 : C
6
H
5
B r » ^ C 523 K
6
[C 6 H 5 (OH) 3 ]
H
5
™
dil. ll 2 SO boil
> C6H5COOH
(unstable)
benzoic acid
26. (c) Only 1° amines give carbylamine reaction (CH 3 ) 2 CHNH 2 + CHC13 + 3KOH(alc.) (CH 3 ) 2 CHNC + 3KC1 + 3H 2 0. Isopropyl carbylamine
27. (d) : Has no resonance structure in which the +ve charge moves to a carbon to which the electronwithdrawing - N 0 2 is attached. 2 8 . I n this reaction S0 2 oxidises H 2 S to S, therefore, S0 2 acts as the oxidising agent. During oxidation four electrons are lost, i.e. S 0 2 + 4eS + 20 2 " Thus, eq. wt. of S0 2 = mol. wt./4 = 64/4 = 16.
29. (d) 4 H3PO3
-A+
3H3PO4 + PH3.
30. (d) : In N2 molecule, one o-bond and two pn-pn bonds are present. 31. (d) :As the size increases from S to Te, the van der Waal's forces of attraction interacting the molecules H2M increase and hence the boiling point increases in that order. However, water has the highest boiling point because of inter molecular H-bonding. Thus, H2S has the lowest boiling point. 32. (hi ;I2 cannot oxidise Br~ to Br2. 33. (b) : Carbocation (a) is antiaromatic and hence is least stable. Carbocation (b), (c) and (d) are all secondary but (b) and (c) are aromatic. Further since (c) is more strained than (b), therefore, (b) is the most stable carbocation. 34. (a) Essential condition for tautomerism is the presence of an a-hydrogen on a saturated carbon attached to C = O, NO, N0 2 , etc. or should have a H-atompresent on aheteroatom (O, N, S, etc.) attached to a double bond. Thus, option (a) does not have a a-hydrogen on a saturated carbon and hence does not exhibit tautomerism. 35. (b): CH,CH2C = CH + HBr
( C 6 H 5 COQ )2 CH 3 CH 2 CH=CHBr
38. (a) 39. (a) :cw-l,2-cyclohexanediol. 40. (d) :2 Nal + Mn0 2 + 3 H 2 S0 4 2 NaHS0 4 + MnS0 4 + 2 H , 0 + I,. 41. (a): Disintegration occurs as : 206 92U + 8 2 He 4 + 6 82 Pb Atoms of Pb present 238
20 6
' • = 0.1 g atom = U decayed 206 Atoms of U present = 23.8 - ().l g atm 238 JV= 0.1 g atom jV0 = U present + U decayed = 0.1 +0.1 =0.2 g atom , _ 2.303x4.5xl09, 02 gl0 0.693 0.1 t = 4.5 x 109 years. (b) While writing the formula of a compound less electronegative element is written first, followed by more electronegative element and accordingly the name is written. As electronegativity values of CI, O, and F are 3, 3.5 and 4 respectively. So the compound of oxygen and fluorine is written as OF2, while compound of oxygen and chlorine is written as
ci2o. (c)
36. (b) : ( C H 33/3 )3COH
2 0 % H
2
S 0
4
>
(CH3)2C = CH2 + H2O 56 g
74!
74 g of /-BuOH give isobutylene = 56 g 37 g of ?-BuOH will give isobutylene = — x37 = 28 Bg 74 But the yield of the reaction = 65% Wt. of isobutylene actually formed _ 28x65 _ | g 2 g 100
37. (a) : Aldols, i.e., P-hydroxyaldehydes or P-hydroxyketones readily undergo dehydration to form a, p-unsaturated aldehydes or ketones O OH „ O OH2 P H H
i-Hydroxyketone -IT, -H,0
O
/
a , (3-Unsaturated k e t o n e
The theoretical dipole moment of HF = 0.92 x 10~10 m x 1.6 x 10 I 9 C = 1.47 x IO"29 Coulomb, metre
1.47 xl0~ 2 9 debye = 4.40 debye t-30 3.335x10" Observed dipole moment = 2 debye (given) Now % of ionic character in HF observed dipole moment = :—, , X100 theoretical dipole moment = - £ - x l 0 0 = 45.45 4.4 42. (a! From Faraday's first law, ^
E
96500 _ IFx96500 _ 0.296x96500 _
31
Ixt ~ 0.5x30x60 Hence equivalent mass of metal = 31.74 As valency of the metal = 2 So atomic mass of the metal = 31.74 x 2 = 63.48 (b) For a first order reaction , [ = M 9 3 2 = M 9 3 2 = 0.023 30 '1/2
lmin-i
Suppose the reaction is CHEMISTRY TODAY | MARCH '08
77
A f=0 a t = 70 ( a - x )
- > product 0 x
Fraction of the reactant remains unreacted Ja-x) a ,T , 2.303, a Now, k,1 = log t a-x or 0.0231 =
70
a-x
a-x
0-0231x70 2.303
a-x or
log
= Q 7 0 2 1
• antilog 0.7021 = 5.036
a-x a
1 _ 0.1985 = 0.2 5.036
(c) 3 M n O f + 4H Mn02 + 2Mn04 + 2H20 In this disproportionation reaction the two half equations are: M n O ^ _ > MnC>4 (change in oxidation number = 1 ) . , „ , „ -.2- Formula weight Equivalent mass of M n 0 4 = Mn04~
M n 0 2 (change in oxidation number = 2) 2- _ Formula weight
Equivalent mass of MnO;
Now equivalent mass of M n 0 4 in the overall reaction undergoing disproportionation FW 1
FW 2
3
3
2
2
43. (a) • The temperature of a glowing splinter is enough to decompose nitrous oxide giving nitrogen and nascent oxygen. The nascent oxygen is more reactive than molecular oxygen, so a glowing splinter burns vigorously in the atmosphere of nitrous oxide. On the other hand molecular oxygen gives off nascent oxygen somewhat at higher temperature than N 2 0 . (b) Ammonia is basic in nature. So it reacts with both concentrated H 2 S0 4 and P 2 0 5 . Therefore these two substances can't be used for drying of NH 3 gas. 2NH 3 + H 2 S0 4 -> (NH 4 ) 2 S0 4 6NH 3 + P 2 0 5 + 3 H 2 0 2(NH 4 ) 3 P0 4 (c) H 2 S reduces ferric chloride to ferrous chloride. Therefore when H 2 S gas is passed through FeCl 3 solution, its brown colour is discharged due to formation of ferrous chloride. 2FeCl, + H,S - > 2FeCl, + 2HC1 + Si 66
CHEMISTRY TOO A Y
MARCH '08
44. (a) : HI is most reactive towards ethanol even in presence of red phosphorus and alcohol is reduced to alkane. (b) The formula C 3 H 8 0 represents, either the compound is an alcohol or ether, as it is saturated and contains one oxygen atom. But the compound is inert to sodium, so it is an ether, because only alcohol reacts with sodium metal. Again the ether when heated with HI yields a mixture of methyl iodide and ethyl iodide, so it is ethyl-methyl ether. C 2 H 5 - O - CH 3 + 2HI — (ethyl methyl ether) C 2 H 5 - 1 + CH 3 - I + H 2 0 (c) A = C 2 H 5 - Cl; B = C 2 H 5 - N 0 2 ; C=C2H5-NH2 D = C 2 H 5 - OH (ethyl alcohol) 45. ( a ) : C 4 H g O is unsaturated and contains one oxygen atom. Further it forms hydrazone derivative, so it may be aldehyde or ketone. As it responds to iodoform reaction but does not reduce Tollen's reagent, so it is 2-ketone. Hence the structural formula is : CHc, - C - CH, - CH, (Butan-2-one) II O (b) A = CH 3 COCl; B = CH 3 -CHO ; OH C = CH 3 - CH - CH 2 - CHO D = CH 3 -CH = CH-CHO (c) The decreasing order of reactivity towards Cannizzaro's reaction i s : H - CHO > (CH 3 ) 3 C - CHO > C 6 H 5 - CHO
• •
wtt& •
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