JR Chemistry - Chapter Wise Important Questions - Part 1

INTER FIRST YEAR CHEMISTRY Chapter wise imp. Questions Designed by SriGayatri SUB: CHEMISTRY

1. ATOMIC STRUCTURE

Long answer type questions 01*. What are the postulates of Bohr’s model of hydrogen atom? Discuss the importance of this model to explain various series of line spectra in hydrogen atom. 02. Explain the salient features of quantum mechanical model of an atom. 03. What are the evidence in favour of dual behavior of electron? 04*. How are the quantum numbers n. 1 and m1 arrived at ? Explain the significance of these quantum numbers. 05. Explain the dueal behavior of matter. Discuss its significance to microscopic par ticles like electrons. Short answer type questions 01*. Show that the circumference of the Bohr ortbit for the hydrogen atom is an integral multiple of the de Broglie wavelength associated with the electron revolving around the orbit. 02. What is a nodal plane? How many nodal planes are possible for 2p- and 3d- orbitals? 03*. Explain the difference between emission and absorption spectra. 04. Explain the difference between orbit and orbital. 05*. Explain photoelectric effect. 06*. Explain briefly the Plank’s quantum theory. 07. What is the wavelenth of light emitted when the electron in a hydrogen atom undergoes transition from an energy level with n = 5 to an energy level with n = 3 ? 08. If the position of the electron is measured within an accurancy of ± 0.002 nm. Calculate the uncertainity in the momentum of the electron. 2. CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES Long answer type questions 01*. Write an essay on s,p,d and f block elements. 02*. What is a periodic property? How the following properties vary in a group and in a period? Explain a) IE , b) EN 03*. Define IE1 and IE2. Why is IE2 > IE1 for a given atom? Discuss the factors that effect IE of an element. 04. How do the following properties change in group-1 and in the third period? Explain with example. a) Atomic radius b) IE c) EA d) Nature of oxides Short answer type questions 01. Give the outer orbit general electronic configuration of a) Noble gases b) Representative elements c) Transition elements d) Inner transition elements 02*. Give any four characteristic properties of transition elements. 03. What is the basic deference between the electron gain enthalpy and electropositivity? 04. What is valency of element? How does it vary with respect to hydrogen in the third period? 05*. What is diagonal relationship? Give a pair of elements having diagonal relationship.Why do they show this relation?

06*. 07.

What is lanthanide contraction? What are its consequences? Write a note on a) Atomic radius b) Metalic radius

c) Covalent radius

3. CHEMICAL BONDING AND MOLECULAR STRUCTURE Long answer type questions : 1. Explain the formation of Ionic Bond with a suitable example. 2. Explain the factors favourable for the formation of Ionic Compounds. 3. Give an account of VSEPR Theory, and its applications. 4*. What do you understand by Hybridisation ? Explain different types of hybridization involvings and p orbitals. 5*. Give the Molecular Orbital Energy diagram of (a) N2 and (b) O2. Calculate the respective bond order. Write the magnetic nature of N2 and O2 molecules. Short answer type questions : 01. State Fajan’s rules and give suitable examples. 02.

Write the resonance structures for NO2, and NO3-

03*. 04. 05. 06*. 07*. 08*. 09*. 10**.

Define Dipole moment. Write its applications. Explain why BeF2, molecule has zero dipole moment although the Be-F bonds are polar. Even though nitrogen in ammonia is in sp3 hybridization, the bond angle deviate from1090 Explain the hybridization involved in PCl5 molecule. Explain the hybridization involved in SF6 molecule. Explain the formation of Coordinate Covalent bond with one example. What is Hydrogen bond? Explain the different types of Hydrogen bonds with ex amples. What is meant by the term Bond order? Calculate the bond orders in the following a) N 2

11. 12.

b) O2

c) O2+

d) O2-

How do you explain the geometry of the molecules on the basis of Valence bond Theory ? How do you predict the shapes of the following molecules making use of VSEPR Theory ?

4. STATES OF MATTER : GASES AND LIQUIDS Long answer type questions 1. Derive the van der waals equation of state. Explain the importance of vander waal’s gas equation. Short answer type questions : 1*. Derive Ideal gas equation. 2*. State and explain Graham’s law Diffusion. 3*. State and explain Dalton’s law of Partial pressures. 4*. Deduce (a) Boyle’s law and (b) Charle’s law from kinetic gas equation. 5*. Deduce (a) Graham’s law and (b) Daltons law from kinetic gas equation. 6*. Derive an expression for kinetic Energy of gas molecules. 7*. Define (a) rms (b) average and (c) most probable speeds of gas molecules. Give their interrela tionship. 8*. Write the postulates of Kinetic Molecular Theory of Gases. 9. Explain the principle underlying the liquefaction of Gases. 10. What is surface tension of liquids ? Explain the effect of temperature on the surface tension of liquids. Jr.Inter Chemistry

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5. STOICHIOMETRY Short answer type questions : 1*. Chemical analysis of a carbon compounds gave the folowing percentage copmposition by weight of the elements present, carbon = 10.06%, hydrogen = 0.84% chlorine = 89.10%,Calculate the empirical formula of the compound. 2*. A carbon compound on analysis gave the following percentage composistion, carbon 14.5%, hydrogen 1.8%, chlorine 64.46%, oxygen 19.24%. Chlorine 64.46%, oxygen 19.24% Calculate the empirical formula of the compound. 3*. Calculate the empirical formula of a compound having percentage composition postassium (k) = 26.57. chromium (cr) = 35.36; oxygen (O) 38.07. (Give the atomic weights of K, cr and O as 39; 52 and 16 respectively) 4*. A carbon compound contains 12.8% carbon, 2.1% hydrogen, 85.1% bromine. The molecular weight of the compound is 187.9. Calculate the molecular formula. 5*. Balance the following redox reactions by ion - electron method : (a) MnO4 − ( aq ) + I − ( aq ) → MnO2 ( S ) (in basic medium) (b) MnO4 − ( aq ) + S O 2 ( g ) → M n 2 + ( a q ) + H S O 4 − ( a q ) (in acidic solution) (c) H 2 O2 ( aq ) + Fe 2 + ( aq ) → Fe 3+ ( aq ) + H 2 O (in acidic solution) (d) Cr2 O7 2 − + SO2 ( g ) → Cr +3 ( aq ) + SO4 2 − (in acidic solution) 6*.

Balancce the following equations in basic medium by ion-electron method and oxidation number methods and identify the oxidising agent and the redusing agent. (a) P4 ( s ) + OH − ( aq ) → PH 3 ( g ) + HPO − 2 ( aq ) (b) N 2 H 4(l ) + ClO3− ( aq ) → NO( g ) + Cl − ( g ) (c) Cl2 O7 ( g ) + H 2 O2 ( aq ) → ClO2 − ( aq ) + O2 ( g ) + H + 6. THERMODYNAMICS

Long answer type questions : 1. Explain the spontaneity of a reaction interms of enthalpy change, entropy change and Gibb’s energy change. Short answer type questions : 1. What are open, closed and isolated systems? Give one example for each. 2. Define the state function and state variables. Give examples 3. “Internal energy is a state function”. Expalin. 4.

Derive the equation for Wrev ’ in isothermal reversible process.

5. 6.

Explain the state function ‘enthalpy,H’. What is the relationship between ∆ U and ∆H ? Explain extensive and intensive properties.

7.

Define heat capacity. What are CP and CV ? Show that CP - CV = R .

8*. 9.

State and explain the Hess’s law of constant Heat summation. Explain the spontaneity of a process?

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10*. 11*. 12*. 13.

What is entropy? Explain with examples. State the second law of thermodynamics and explain it. State the third law of thermodynamics. What do you understand by it ? Explain spontaneity of a process in terms of Gibbs energy. 7. CHEMICAL AND IONIC EQUILIBRIUM Long answer type questions : 1*. What is Lechatlier’s principle? Discuss briefly the factor s which can influence the equilibrium. 2*. Discuss the application of Lechatelier’s principle for the industrial synthesis of Ammonia and sulphur trioxide. 3*. Explain the concept of Bronsted acids and Bronsted bases, Illustrate the answer with suitable examples. 4*. Explain Lewis acid-base theory with suitable example. Classify the following species into Lewis acids and Lewis bases and show these act as Lews acid / base. b) Fc) H + d) Bcl3 a) OH 5*. Define pH.. what is buffer solution ? Derive Henderson - Hasselbalch equation for Calculating the pH of an acid buffer solution. 6*. Explain the term “Hydrolysis of salts” with examples.Discuss the pH of the follow ing types of salt solutions. i) Salts of weak and strong base. ii) Salts of strong acid and weak base. Short answer type questions : 1.

Write expression for the equilibrium constant, K c , for each of the following reactions.  → 2 NOg + CI 2( g ) (i) 2 NOCI g ← 

2. 3. 4*. 5*.

How does the value of equilibrium constant predict the extent of reaction ? Explian the terms : i) extent of ionization and on what factors it depends.ii) dissociation iii) ionization Explain the Arrhenius concept of acids and bases. What is conjugate acid-base pair ? Illustrate with examples.

6.

Write equation that shows H 2 PO4 - acting both as an acid and as a base.

7.

Write the conjugate acid and conjugate base of each of the following : a) OH -

8*. 9*. 10*.

b) H 2O

(c) HCO3 -

(d) H 2O2

Define ionic product of water. What is its value at room temperature ? What is common ion effect ? Illustrate. Define solubility product ? Write solubility product expressions for the following : i) Ag 2Cr2O7

ii) Zr3 ( PO4 )4

11*.

Give the classification of salts. What type of salts undergo hydrolysis ?

12*.

Aqueous solution of NH 4 CI is acidic. Explain.

13*.

Aqueous solution of CH 3COONa is basic explain.Long answer questions 8. HYDROGEN AND ITS COMPOUNDS

Short answer type questions 1*. Explain the terms hard water and soft water. Write a note on the i) ion-exchange method and ii) Calgon method for the removal of hardness of water Jr.Inter Chemistry

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2*. 3*. 4*. 5.

Write the chemical reaction to justify that hydrogen peroxide can function as on oxidizing as well as reducing agent. Write a note on heavy water. Discuss the principle and the method of softening of hard water by synthetic, ion- exchange resins. In how many ways can you express the strength of H2O2 ? Calculate the strength of 15 volume solution of H2O2 in g/l. Express this strength in normality and molarity. 9. THE S-BLOCK ELEMENTS

Long answer type questions : 1. Discuss the preparation of sodium carbonate. 2.* Explain the significance of sodium, postassium, magnesium and calcium in biologi cal fluids. 3*. Write a few lines about cement. Short answer type questions : 1*. What do you know about Castner-Kellner process? Write the principle involved in it. 2. Write a note on the anomalous behavior of Beryllium. 3*. What is plaster of Paris?Write a short note on it. 4. How do you obtain pure sodium chloride from a crude sample ? 5. When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change. 10. THE P-BLOCK ELEMENTS - GROUP 13 Long answer type questions : 1*. Write any two methods of preperation of diborane. How does it react with a) Carbon monoxide and b) Ammonia ? Short answer type questions : 1*. Explain borax bead test with a suitable example. 2*. Explain the structure of diborane. 3. Explain the reactions of aluminium with acids. 4*. Give two methods of preparation of diborane. 5*.

How does diborane react with a) H 2 O

b) CO

c) N (CH 3 )3 ?

11. THE P-BLOCK ELEMENTS - GROUP 14 Long answer type questions : 1*. Write note on the allotropy of carbon. Short answer type questions : 1*. Explain the difference in properties of diamond and graphite on the basis of their structure. 2*. Write a short note Zeolites. 3. Write a short note silicates. 4*. What are silicones? How are they obtained? 5. Write a short notes on fullerene. 6*. Why is diamond hard? 7.

What happens when a) CO 2 is passed through slaked lime b) CaC2 is heated with N 2 .

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VERY SHORT ANSWER TYPE QUESTIONS 1. ATOMIC STRUCTURE 1.

Calculate the charge of one mole of electrons.

Ans : One electron has charge - 1.602 × 10 −19 coloumbs one mole of electrons has charge −6.023 × 1023 × 1.602 × 10−19 2.

= 9.648846 × 104 = 96488.5 coloumbs Calculate the mass of one mole of electrons.

Ans : Mass of electron = 9.1×10−31 kg ( or ) 9.1×10−28 gms. One moel of electrons has mass 6.023 × 1023 × 9.1× 10−31 = 54.8 × 10−8 = 5.48 × 10−7 kg . 3.

How many p electrons are present in sulphur atom ?

Ans : Sulphur has electronic configuration 1s 2 2s 2 2p6 3s 2 3p4 ∴ Sulphur has 10 'p' electrons. 4. What are the values of principal quantum number (n) and azimuthal quantum number (l) for a 3d electron ? Ans : For a 3d - electron principal quantum number (n) = 3 and Azimuthal quantum number (l) = 2. 5. What is the completer symbol for the atom with the given atomic number (Z) and atomic mass (A) ? i) Z = 4, A= 9 : ii) Z = 17, A = 35 : iii) Z = 92, A = 233.

Ans : i ) Z = 4, A = 9 Complete symbol is 4 Be9 ii) Z = 17,A = 35 Complete symbol is 17 Cl35 iii) Z = 92,A = 233 Complete symbol is 6.

92

U 233

What is the frequency of radiation of wavelength 600 nm ?

Ans : Formulae υ = =

c

λ

3 × 108 1 × 1015 −7 = 6 × 10 2

= 0.5 × 1015 = 5 × 1014 sec −1

λ = 600 nm = 600 ×10−9 m = 6 ×10−7 m C = 3 × 108 m / sec 7. What is Zeeman effect ? Ans : The splitting up of spectral lines in presence of strong exetrnal magnetic field is called as Zeeman effect . 8. What is Stark effect ? Ans : The splitting of spectral lines in presence of strong electric field is called as Stark effect.

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9.

Electrons are emitted with zero velocity from a metal surface when it is exposed to radition o f

0 . What is the threshold frequency (v0) ? wavelength 4000 A Ans : Formulae

1 hv = hv0 + mv 2 ⇒ 2

1 2 hv = hv0 + m ( o ) 2

hv = hv0 0

λ = 4000 Α = 4 × 103 × 10 −10 = 4 × 10−7 m.

υ = 0 , C = 3 x 108 m/sec. ⇒ v = v0

∴v =

c

λ

=

3×108 3 15 = ×10 4×10−7 4

= 0.75 × 1015 = 7.5 × 1014 sec −1 .

10. Which of the following orbitals are possible ? 2s,1p,3f,2p. Ans : 2s,2p orbitals are possible among 2s,1p,3f,2p and 1p, 3f orbitals ar not possible. 11. How many electrons in an atom may have n = 4 and m = +1/2 ? Ans : For n = l values are 0,1,2,3

l = 0 → s contains are electron with ms = +1/2 l = 1 → p contains 3 electron with ms = +1/2 l = 2 → d contains 5 electron with ms= +1/2

l = 3 → f contains 7 electron with ms= +1/2 ∴ Total no.of electrons with ms= +1/2 for n = 4 = 1 + 3 + 5 + 7 = 16. 2. CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES 1. What is the difference in the approach between the Mendeleev's periodic law and the modern periodic law ? Ans : → According to Mendeleev the physical and chemical properties of elements are periodic functions of their atomic weights. → According to modern periodic law physical and chemical properties of elements are periodic functions of their atomic numbers. 2. In terms of period and group, where would you locate the element with Z = 114 ? Ans : Element Z = 114 is present in 17th period and IVA group (Group - 14) 3. Write the atomic number of the element, present in the third period and seventeenth group of the periodic table. Ans : The Element present in 3rd period and Group - 17 (VIIA group) is chlorine (Cl) It's atomic number is 17. 4. Which element do you think would have been named by a) Lawrence Berkeley Laboratory Jr.Inter Chemistry

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b) Seaborg's group Ans : a) Lawrence Berkeley (Laboratory-Lanthanide) b) Seaborg's group - Actinide (Transuranic element ) 5. What are representative elements ? Give their valence shell configuration. Ans : → Representative elements are s and p-block elements except zero group. → These have general electronic configuration ns1-2 np1-5 6. Give the outer shells configuration of d-block and f-block elements. Ans : → The outer shell electronic configuration of d-block- elements is ns1-2 (n-1)d1-10 → The outer shell electronic configuration of f-block - elements is ns1-2 (n-1)d0 (or) 1 (n-2) f1-14 7. Name the anomalous pairs of elements in the Mendaleev's periodic table. Ans : In Mendelleev's periodic table anamalous pairs are the elements whose atomic weights increasing order is reversed. Te

Eg : 1) 8.

I

127.6 126.9

Co

2)

Ni

58.93 58.69

Among N -3 ,O-2 ,F- ,Na + ,Mg +2 and Al+3

a. What is common in them ? b. Arrange them in the increasing ionic radii. Ans : Given ions are N -3 ,O-2 ,F- ,Na + ,Mg +2 and Al+3 . a) The above ions have same number of electrons (All have 10 electrons ). So these are called iso electronic species. b) The increasing order of ionic radii among above ions is Al+3