CBSE 2014 Question Paper for Class 12 Chemistry - Foreign

AglaSem Schools

H$moS> Z§.

Series OSR/2

Code No.

amob Z§.

56/2/1

narjmWu H$moS >H$mo CÎma-nwpñVH$m Ho$ _wI-n¥ð >na Adí` {bIo§ &

Roll No.

Candidates must write the Code on the title page of the answer-book.

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Please check that this question paper contains 15 printed pages. Code number given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate. Please check that this question paper contains 30 questions. Please write down the Serial Number of the question before attempting it. 15 minutes time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer-book during this period.

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H¥$n`m Om±M H$a b| {H$ Bg àíZ-nÌ _o§ _w{ÐV n¥ð> 15 h¢ & àíZ-nÌ _| Xm{hZo hmW H$s Amoa {XE JE H$moS >Zå~a H$mo N>mÌ CÎma -nwpñVH$m Ho$ _wI-n¥ð> na {bI| & H¥$n`m Om±M H$a b| {H$ Bg àíZ-nÌ _| >30 àíZ h¢ & H¥$n`m àíZ H$m CÎma {bIZm ewê$ H$aZo go nhbo, àíZ H$m H«$_m§H$ Adí` {bI| & Bg àíZ-nÌ H$mo n‹T>Zo Ho$ {bE 15 {_ZQ >H$m g_` {X`m J`m h¡ & àíZ-nÌ H$m {dVaU nydm©• _| 10.15 ~Oo {H$`m OmEJm & 10.15 ~Oo go 10.30 ~Oo VH$ N>mÌ Ho$db àíZ-nÌ H$mo n‹T>|Jo Am¡a Bg Ad{Y Ho$ Xm¡amZ do CÎma-nwpñVH$m na H$moB© CÎma Zht {bI|Jo &

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agm`Z {dkmZ (g¡ÕmpÝVH$) CHEMISTRY (Theory)

{ZYm©[aV g_` : 3 KÊQ>o

A{YH$V_ A§H$ : 70

Time allowed : 3 hours 56/2/1

Maximum Marks : 70 1

P.T.O.

AglaSem Schools

gm_mÝ` {ZX}e : g^r àíZ A{Zdm`© h¢ &

(ii)

àíZ-g§»`m 1 go 8 VH$ A{V bKw-CÎmar` àíZ h¢ & àË`oH$ àíZ Ho$ {bE 1 A§H$ h¡ &

(iii)

àíZ-g§»`m 9 go 18 VH$ bKw-CÎmar` àíZ h¢ & àË`oH$ àíZ Ho$ {bE 2 A§H$ h¡§ &

(iv)

àíZ-g§»`m 19 go 27 VH$ ^r bKw-CÎmar` àíZ h¢ & àË`oH$ àíZ Ho$ {bE 3 A§H$ h¢ &

(v)

àíZ-g§»`m 28 go 30 VH$ XrK©-CÎmar` àíZ h¢ & àË`oH$ àíZ Ho$ {bE 5 A§H$ h¢ &

(vi)

Amdí`H$VmZwgma bm°J Q>o~bm| H$m à`moJ H$a| & H¡$ëHw$boQ>am| Ho$ Cn`moJ H$s AZw_{V Zht h¡ &

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(i)

General Instructions : All questions are compulsory.

(ii)

Questions number 1 to 8 are very short-answer questions and carry 1 mark each.

(iii)

Questions number 9 to 18 are short-answer questions and carry 2 marks each.

(iv)

Questions number 19 to 27 are also short-answer questions and carry 3 marks each.

(v)

Questions number 28 to 30 are long-answer questions and carry 5 marks each.

(vi)

Use Log Tables, if necessary. Use of calculators is not allowed.

1.

\o$Z ßbdZ {d{Y _| A`ñH$m| H$mo gm{ÝÐV H$aZo _| g§J«mhH$m| h¡ ?

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(i)

(collectors) H$m

Š`m H$m`© hmoVm 1

What is the function of collectors in the froth floatation process for the concentration of ores ? 2.

^m¡{VH$ A{YemofU hmoZo _| {H$g àH$ma Ho$ ~b CÎmaXm`r hmoVo h¢

?

What type of forces are responsible for the occurrence of physisorption ? 56/2/1

2

1

AglaSem Schools 3.

EH$b

N–N

Am~ÝY EH$b

P–P

?

Am~ÝY go Xþ~©b Š`m| hmoVm h¡

1

Why is the single N – N bond weaker than the single P – P bond ? 4.

{ZåZ{b{IV g§H$a {H$g àH$ma H$s g_md`dVm

(isomerism) àX{e©V

H$aVm h¡

:

1

[Co(NH3)6][Cr(CN)6] What type of isomerism is shown by the following complex : [Co(NH3)6][Cr(CN)6] b.c.c.

EoH$H$ gob _| na_mUw {ÌÁ`m gå~ÝY H$mo ì`º$ H$s{OE &

(r)

Am¡a gob Ho$ {H$Zmao H$s bå~mB©

(a)

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5.

Ho$ Amngr 1

Express the relationship between atomic radius (r) and the edge length (a) in the b.c.c. unit cell. (IUPAC) Zm_

{b{IE

as

{ZåZ{b{IV `m¡{JH$ H$m AmB©.`y.nr.E.gr.

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6.

BZ XmoZm| _| go H$m¡Z-gm A{YH$ jmar` h¡ Am¡a Š`m|

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1

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Write the IUPAC name of the following compound :

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Which of the two is more basic and why ?

8.

ñQ>mM© ~ZmZo dmbo

-½byH$moµO

Ho$ Xmo KQ>H$m| Ho$ Zm_ {b{IE &

1

Name the two components of -glucose which constitute starch.

56/2/1

3

P.T.O.

AglaSem Schools 9.

Ho$ EH$ {db`Z H$m ßb¡{Q>Z_ Ho$ BboŠQ´>moS>m| Ho$ ~rM 5.0 Eoånr`a {dÚwV² Ymam go 20 {_ZQ> VH$ d¡ÚwV AnKQ>Z {H$`m J`m & H¡$WmoS> na {ZH¡$b H$m {H$VZm Ðì`_mZ {Zjo{nV hmoJm ? Ni(NO3)2

2

({X`m J`m h¡ : {ZH¡$b H$m na_mUw Ðì`_mZ = 58.7 g mol–1, 1 F = 96500 C mol–1) A solution of Ni(NO3)2 is electrolysed between platinum electrodes using a current of 5.0 ampere for 20 minutes. What mass of nickel will be

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deposited at the cathode ?

(Given : At. Mass of Ni = 58.7 g mol–1, 1 F = 96500 C mol–1)

(i)

eyÝ` H$mo{Q> H$s A{^{H«$`m

(ii)

àW_ H$mo{Q> H$s A{^{H«$`m

2

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A{^{H«$`m H$s AY© Am`w H$s n[a^mfm {b{IE & {ZåZ Ho$ AY© Am`w Ho$ {b`o ì`§OH$ {b{IE :

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10.

(ii)

first order reaction.

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zero order reaction and

{gëda A`ñH$ go {gëda Ho$ {ZîH$f©U go gå~Õ amgm`{ZH$ A{^{H«$`mE± {b{IE &

2

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11.

(i)

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Define half-life of a reaction. Write the expression of half-life for

12.

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Write the chemical reactions involved in the extraction of silver from silver ore.

gëµ\$a Ho$ Xmo A{V _hÎdnyU© Anaê$nm| Ho$ Zm_ {b{IE & BZ XmoZm| _| go H$m¡Z-gm H$j Vmn na ñWm`r hmoVm h¡ ? Š`m hmoVm h¡ O~ ñWm`r ê$n H$mo 370 K go D$na Ja_ {H$`m OmVm h¡ ?

2

AWdm

56/2/1

(i)

gånH©$ {d{Y go H2SO4 H$s àm{á H$mo A{YH$V_ ~ZmZo Ho$ à{V~ÝY {b{IE &

(ii)

Ob _§o

H2SO4 Ho$

{bE Ka2 H$s Amn SN2 {H«$`m{d{Y Ûmam A{YH$ Vrd«Vm go A{^{H«$`m H$aZo H$s Amem H$a|Jo Am¡a Š`m| ? CH3 – CH2 – CH – CH3  Br

(b)

SN1 A{^{H«$`mAm|

(a)

Which alkyl halide from the following pairs would you expect to react more rapidly by an SN2 mechanism and why ?

?

2

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_| ao{g_rH$aU hmo OmVm h¡ & Š`m|

CH3 – CH2 – CH – CH3 CH3 – CH2 – CH2 – CH2 – Br  Br Racemisation occurs in SN1 reactions. Why ?

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(b)

{ZåZ A{^{H«$`m H$s {H«$`m{d{Y {b{IE :

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17.

CH3 – CH2 – CH2 – CH2 – Br

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HBr CH3CH2OH   CH3CH2Br  H2O

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Write the mechanism of the following reaction :

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{ZåZ A{^{H«$`mAm| _| à`wº$ A{^H$maH$m| Ho$ Zm_ {b{IE : (i) µ\$sZm°b Ho$ ~«mo_rZoeZ go 2,4,6-Q´>mB©~«mo_moµ\$sZm°b ~ZmZm (ii) ã`yQ>oZ-2-AmoZ go ã`yQ>oZ-2-Amob ~ZmZm (iii) Eo{Zgmob H$m \«$sS>ob – H«$mµâQ²>g EopëH$brH$aU (iv) àmW{_H$ EoëH$mohm°b Ho$ Am°ŠgrH$aU Ûmam H$m~m©opŠg{bH$ Aåb ~ZmZm

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18.

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HBr CH3CH2OH   CH3CH2Br  H2O

Name the reagents used in the following reactions :

56/2/1

(i)

Bromination of phenol to 2,4,6-tribromophenol

(ii)

Butan-2-one to Butan-2-ol

(iii)

Friedel − Crafts alkylation of anisole

(iv)

Oxidation of primary alcohol to carboxylic acid 6

2

AglaSem Schools (i)

KCl {H$g

(ii)

{g{bH$m°Z H$mo

(iii)

{ZåZ _| go H$m¡Z-gm AmpÊdH$ R>mog H$m CXmhaU h¡ CO2 AWdm SiO2

(iv)

BZ_| go H$m¡Z-gm A{YH$ AÀN>o Mwå~H$ ~ZmEJm, \o$amoMwå~H$s` nXmW© AWdm \o$arMwå~H$s` nXmW© ?

àH$ma H$m agg_rH$aU{_Vr` Xmof {XImVm h¡ Am¡a Š`m|

S>mo{nV H$aZo na {H$g àH$ma H$m AY©MmbH$ ~ZVm h¡

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As go

?

(i)

What type of stoichiometric defect is shown by KCl and why ?

(ii)

What type of semiconductor is formed when silicon is doped with As ?

(iii)

Which one of the following is an example of molecular solid :

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CO2 or SiO2

What type of substances would ferromagnetic or ferrimagnetic ?

(i)

gmYmaU gob H$s VwbZm _|

(ii)

ZrMo Xr JB© gob A{^{H«$`m Ho$ {b`o gmå` pñWam§H$

make

better

magnets,

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BªYZ gob Ho$ Xmo bm^ {b{IE &

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H2 – O2

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20.

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(iv)

(Kc) 10

h¡ & BgHo$ {b`o

o

gob

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n[aH${bV H$s{OE &

E

3

(i)

Write two advantages of H2 – O2 fuel cell over ordinary cell.

(ii)

Equilibrium constant (Kc) for the given cell reaction is 10. o

Calculate Ecell .

56/2/1

7

P.T.O.

AglaSem Schools 21.

pñWa Am`VZ AdñWm _| hþE Wo :

SO2Cl2

Ho$ àW_ H$mo{Q> Ho$ D$î_r` AnKQ>Z _| {ZåZ Am§H$‹S>o àmá

SO2Cl2 (g)  SO2 (g)  Cl2(g)

1

0

0 .4

2

100

0 .7

doJ pñWam§H$ n[aH${bV H$s{OE & ({X`m J`m h¡ : log 4 = 0.6021,

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g_`/s−1 gH$b Xm~/atm

à`moJ

log 2 = 0.3010)

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1

0

Total pressure/atm

.a

Time/s−1

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Experiment

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SO2Cl2 (g)  SO2 (g)  Cl2(g)

0 .4 0 .7

100

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2

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The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume :

(b) (c)

56/2/1

R>mogm| na J¡gm| Ho$ A{YemofU Ho$ {bE \«$m°`ÝS>{bH$ A{YemofU g_Vmnr (isotherm) Ho$ {bE EH$ g_rH$aU Ho$ ê$n _| ì`§OH$ {b{IE & _ŠIZ Ho$ n[a{já àmdñWm Am¡a n[ajon _mÜ`_ Š`m h¢ ? g_wÐ Am¡a ZXr Ho$ {_bZo Ho$ ñWmZ na S>oëQ>m ~ZVm h¡ & Š`m| ?

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(a)

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22.

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Calculate the rate constant. (Given : log 4 = 0.6021, log 2 = 0.3010)

(a)

Write the expression for the Freundlich adsorption isotherm for the adsorption of gases on solids, in the form of an equation.

(b)

What are the dispersed phase and dispersion medium of butter ?

(c)

A delta is formed at the meeting place of sea and river water. Why ? 8

3

AglaSem Schools 23.

(a)

b¡ÝWoZm°`S> H$m¡Z-H$m¡Z gr {d{^Þ CnMm`r AdñWmE± {XImVo h¢

(b)

g§H«$_U VÎdm| H$s Xmo {deofVmE± {b{IE &

(c)

3d-ãbm°H$ Š`m| ?

?

Ho$ VÎdm| _| go {H$Z-{H$Z H$mo g§H«$_U VÎd Zht _mZm Om gH$Vm h¡ Am¡a 3

AWdm {ZåZ Ho$ {bE Cn`wº$ H$maU {b{IE

:

+3

AnZr

(b)

Sc (Z = 21)

(c)

Obr` {db`Z _|o

(a)

What are the different oxidation states exhibited by the lanthanoids ?

(b)

Write two characteristics of the transition elements.

(c)

Which of the 3d-block elements may not be regarded as the transition elements and why ?

grarµO Ho$ VÎdm| _| go

hmoVm h¡ O~{H$

Ti3+ a§JrZ

Zn

H$s

hmoVm h¡ &

3

OR

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Sc3+ a§JhrZ

3d

as

go Zn (Z = 30) VH$ Ho$ na_mUwH$aU H$s EoÝW¡ënr g~go H$_ hmoVr h¡ &

`m¡{JH$mo§ H$s VwbZm _|

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Am°ŠgrH$aU AdñWm H$mo àmá H$aZo Ho$ {bE 2+ Mn `m¡{JH$ A{YH$ ñWm`r hmoVo h¢ &

Fe2+

(a)

(a)

(b)

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Assign suitable reasons for the following : The Mn2+ compounds are more stable than Fe2+ towards oxidation to their + 3 state. In the 3d series from Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomization of Zn is the lowest. (c)

56/2/1

Sc3+ is colourless in aqueous solution whereas Ti3+ is coloured.

9

P.T.O.

AglaSem Schools 24.

{ZåZ A{^{H«$`mAm| _|

A, B Am¡a C H$s

g§aMZmE± ~VmBE :

3

(i)

HNO2 LiAlH4 KCN CH3Br  A   B   C 273 K

(ii)

NH3 CHCl  NaOH Br2  KOH CH3COOH   A    B 3   C 

Give the structures of A, B and C in the following reactions :

(ii)

NH3 CHCl  NaOH Br2  KOH CH3COOH   A    B 3   C 

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HNO2 LiAlH4 KCN CH3Br  A   B   C 273 K

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3

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Define the following terms :

as

{ZåZ nXm| H$s n[a^mfmE± {b{IE : (a) EoZmo_a (b) àmoQ>rZm| H$m {dH¥$VrH$aU (c) Amdí`H$ Eo_rZmoo Aåb

ls

25.

(i)

Anomers

(b)

Denaturation of proteins

(c)

Essential amino acids

(i)

(iii)

EoÝQ>r{hñQ>m_rZ H$s EH$ CXmhaU g{hV n[a^mfm {b{IE & {ZåZ Am¡f{Y`m| _| go H$m¡Z-gr à{VO¡{dH$ h¡ : _m°\$s©Z, BŠdm{Zb, ŠbmoaEoå\µ ¡${ZH$mob, Eopñn[aZ & EoñnmQ>©o_ H$m Cn`moJ R>§S>o ^moOZ Am¡a no` nXmWmªo VH$ gr{_V Š`m| hmoVm h¡

(i)

Define Antihistamine with an example.

(ii)

Which one of the following drugs is an antibiotic : Morphine, Equanil, Chloramphenicol, Aspirin.

(iii)

Why is use of aspartame limited to cold food and drink ?

56/2/1

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(ii)

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26.

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(a)

10

?

3

AglaSem Schools 27.

ßbmpñQ>>H$ Ho$ W¡bm| na à{V~ÝY bJ OmZo Ho$ CnamÝV, EH$ ñHy$b Ho$ N>mÌm| Zo {ZU©` {b`m {H$ dh bmoJm| H$mo dmVmdaU Am¡a `_wZm ZXr na ßbmpñQ>>H$ Ho$ W¡bm| Ho$ hm{ZH$maH$ à^mdm| go gy{MV H$a|Jo & ~mV H$mo A{YH$ à^mdr ~ZmZo Ho$ {bE, CÝhm|Zo Xÿgao ñHy$bm| Ho$ gmW {_bH$a EH$ a¡br aMr Am¡a gpãµO`m± ~oMZo dmbm|, XþH$mZXmam| Am¡a {S>nmQ>©_oÝQ>b ñQ>moam| _| H$mµJµO Ho$ W¡bo ~m±Q>o & g^r N>mÌm| Zo àU {H$`m {H$ do `_wZm ZXr H$mo ~MmZo Ho$ {bE ^{dî` _| nm°brWrZ

Cn`w©º$ boIm§e H$mo n‹T>H$a {ZåZ àíZm| Ho$ CÎma Xr{OE

:

(i)

N>mÌm|§o Zo {H$Z _yë`m| H$mo Xem©`m h¡

(ii)

O¡d-{ZåZrH$aUr` ~hþbH$ Š`m hmoVo h¢ ? EH$ CXmhaU Xr{OE &

(iii)

Š`m nm°brWrZ EH$ g_ (hmo_mo) ~hþbH$ h¡ AWdm gh (co-) ~hþbH$ h¡

3

?

.a

gl

as

?

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Ho$ W¡bm| H$m à`moJ Zht H$a|Jo &

ls

After the ban on plastic bags, students of one school decided to create

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awareness among the people about the harmful effects of plastic bags on

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the environment and the Yamuna river. To make it more impactful, they organized a rally by joining hands with other schools and distributed

w

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paper bags to vegetable vendors, shopkeepers and departmental stores.

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All students pledged not to use polythene bags in future to save the

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Yamuna river. After reading the above passage, answer the following questions :

56/2/1

(i)

What values are shown by the students ?

(ii)

What are biodegradable polymers ? Give one example.

(iii)

Is polythene a homopolymer or copolymer ?

11

P.T.O.

AglaSem Schools (a) (b)

(a)

Ob _| 10 g CaCl2 KmobZo go àmá hþE {db`Z Ho$ {bE ŠdWZm§H$ CÞ`Z H$mo n[aH${bV H$s{OE & (Ob Ho$ {bE Kb = 0.512 K kg mol–1, CaCl2 H$m _moba Ðì`_mZ = 111 g mol–1) AWdm {ZåZ nXm| H$s n[a^mfmE± {b{IE : (i)

pñWaŠdmWr (Eo{µO`moQ´>mon)

(ii)

namgaUr (Amog_m°{Q>H$) Xm~

(iii)

AUwg§»` (H$mo{bJo{Q>d) JwUY_©

9.8% (w/w) H2SO4 Ho$ {db`Z H$s _mobaVm n[aH${bV H$s{OE `{X Bg {db`Z H$m KZËd 1.02 g ml–1 hmo & (H2SO4 H$m _moba Ðì`_mZ = 98 g mol–1)

gl

State Raoult’s law for a solution containing volatile components.

oo

Calculate the boiling point elevation for a solution prepared by

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(b)

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Name the solution which follows Raoult’s law at all concentrations and temperatures.

(b)

56/2/1

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adding 10 g of CaCl2 to 200 g of water. (Kb for water = 0.512 K kg mol–1, Molar mass of CaCl2 = 111 g mol–1) OR

Define the following terms :

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(a)

(i)

Azeotrope

(ii)

Osmotic pressure

(iii)

Colligative properties

3

3

.a

(a)

2

200 g

as

(b)

dmînerb Ad`dm| dmbo {db`Z Ho$ {bE amCëQ> {Z`_ {b{IE & g^r gmÝÐUm|o Am¡a VmnH«$_m| na amCëQ> {Z`_ AZwgma ahZo dmbo {db`Z H$m Zm_ {b{IE &

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28.

Calculate the molarity of 9.8% (w/w) solution of H2SO4 if the density of the solution is 1.02 g ml–1. (Molar mass of H2SO4 = 98 g mol–1) 12

2

AglaSem Schools (a)

{ZåZ Ho$ H$maU ~VmBE : (i) + 5 AdñWm _| Bi à~b CnMm`H$ hmoVm h¡ & (ii) PCl5 Vmo OmZm OmVm h¡ naÝVw NCl5 Zht & (iii) bm¡h HCl _| KwbH$a FeCl2 ~ZmVm h¡, FeCl3 Zht &

3

(b)

{ZåZ H$s g§aMZmE± ~ZmBE :

2

(i)

XeOF4

(ii)

HClO4

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29.

AWdm H2S2O8

(ii)

bmb

as

{ZåZ Ho$ H$maU {b{IE

:

3

dmîn AdñWm _| JÝYH$ (gë\$a) AZwMwå~H$Ëd àX{e©V H$aVm h¡ &

(ii)

µOrZm°Z go {^Þ, hr{b`_ H$m H$moB© ñnîQ amgm`{ZH$> `m¡{JH$ kmV Zht h¡ &

(iii)

H3PO3 go H3PO2 EH$

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.a

gl

(i)

A{YH$ à~b AnMm`H$ h¡ &

Account for the following : (i)

Bi is a strong oxidizing agent in the + 5 state.

(ii)

PCl5 is known but NCl5 is not known. Iron dissolves in HCl to form FeCl2 and not FeCl3.

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(iii)

Draw the structures of the following :

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(b)

P4

ch

(a)

(i)

2

.s

(b)

{ZåZ H$s g§aMZmE± ~ZmBE :

w

(a)

(i)

XeOF4

(ii)

HClO4 OR

(a)

56/2/1

Draw the structures of the following : (i)

H2S2O8

(ii)

Red P4 13

P.T.O.

AglaSem Schools Account for the following : (i) Sulphur in vapour state exhibits paramagnetism. (ii) Unlike xenon, no distinct chemical compound of helium is known. (iii) H3PO2 is a stronger reducing agent than H3PO3.

(a)

EoWoZ¡b Ho$ {ZåZ A{^H$maH$m| Ho$ gmW A{^{H«$`m H$aZo na ~Zo CËnmXm| H$mo {b{IE (i) CH3MgBr go Am¡a {\$a H3O+ go (ii) Zn-Hg/gmÝÐ HCl go

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30.

(b)

(b)

VZw NaOH H$s CnpñW{V _| C6H5CHO go {ZåZ `m¡{JH$ `w½_m§o _| nañna ^oX H$aZo Ho$ {bE gab amgm`{ZH$ narjU Xr{OE (i) ~oݵOmoBH$ Aåb Am¡a E{Wb ~oݵOmoEQ> (ii) àmonoZ¡b Am¡a ã`yQ>oZ-2-AmoZ AWdm

:

as

(iii)

:

{ZåZ Ho$ H$maU {b{IE : (i) HCN Ho$ gmW A{^{H«$`m H$aZo _| CH3COCH3 go CH3CHO A{YH$ A{^{H«$`merb hmoVm h¡ & (ii) go_rH$m~©oµOmBS> (H2NNHCONH2) _| Xmo – NH2 J«wn hmoVo h¢ & {\$a ^r go_rH$m~m©µOmoZ ~ZmZo _| Ho$db EH$ – NH2 J«wn {H«$`mH$mar hmoVm h¡ &

(b)

{ZåZ Zm_Ymar A{^{H«$`mAmo§ Ho$ {bE amgm`{ZH$ g_rH$aU {b{IE (i) amoµOoZ_wÝS A{^{H«$`m (ii) hob-dmobmS>©-µOo{bÝñH$s A{^{H«$`m (iii) H¡$ZrµOmamo A{^{H«$`m

2

2

:

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w

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ch

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ls

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gl

(a)

3

(a)

56/2/1

Write the products formed when ethanal reacts with the following reagents : (i)

CH3MgBr and then H3O+

(ii)

Zn-Hg/conc. HCl

(iii)

C6H5CHO in the presence of dilute NaOH 14

3

AglaSem Schools (b)

Give simple chemical tests to distinguish between the following pairs of compounds : (i)

Benzoic acid and Ethyl benzoate

(ii)

Propanal and Butan-2-one OR

CH3CHO is more reactive than CH3COCH3 towards reaction with HCN.

(ii)

There are two – NH2 groups in semicarbazide (H2NNHCONH2). However, only one is involved in the formation of semicarbazone.

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(i)

Write the chemical equation to illustrate each of the following name reactions :

.a

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(b)

Account for the following :

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(a)

Rosenmund reduction

(ii)

Hell-Volhard-Zelinsky reaction

(iii)

Cannizzaro reaction

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w

w

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ch

oo

ls

(i)

56/2/1

15

2,800 P.T.O.

AglaSem Schools

MARKING SCHEME Chemistry – 2014 FOREIGN – SET (56/2/1)

a or 4r =√3 a 2 – hydroxybenzaldehyde CH3 – NH2 ,because of the electron releasing (+I effect) tendency of methyl group Amylose and amylopectin m= z I t I=5 A t= 20 x 60s = 1200s atomic mass m= n x F xIxt

om

6 7 8 9

√3 r= 4

.c

4 5

Collectors enhance non-wettability of the mineral/ore particles van der Waals forces Because of high inter-electronic repulsion of non bonding electrons owing to the small bond length / atomic size Coordination isomerism

em

1 2 3

.

as

4Ag + 8 CN- + 2H2O + O2 → 4 [Ag(CN)2] - + 4 OH2[Ag(CN)2] - + Zn → [Zn(CN)4] - 2 + 2Ag Or Ag2S + 4NaCN → 2 Na[Ag(CN)2] + Na2S 2Na[Ag(CN)2] + Zn → Na2 [Zn(CN)4] + 2Ag (balancing of equation is not necessary) Rhombic and Monoclinic Rhombic Sulphur Rhombic sulphur changes to monoclinic sulphur OR a) High pressure and low temperature b) Because ionization of HSO-4 is difficult / removal of proton from negatively charged HSO-4 is difficult.

1 1 1 ½+½ 1 ½ ½ 1 1 ½+½ 1 1

13

14

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12

w

w

12

.s

ch

oo

11

ls

.a

gl

10

m=2 x 96500 C x 5 A x 1200 s m= 1.825 g (or any other suitable method) Half-life of a reaction is the time in which the concentration of a reactant is reduced to half of its initial concentration. (i) (ii)

1 1 1

(i) (ii) Hydridization : sp3d2 shape– octahedral IUPAC – hexafluoridocobaltate(III)

1

1 ½ ½ 1 1 1 1 ½+½ 1

AglaSem Schools

15

(i) (ii)

CH3 CH2- Cl + KOH (aq) → CH3 CH2 –OH +KCl

1

1

HBr → H + Br +

½+½ 1

-

½

½

gl

as

em

.c

17

a) 1-Bromobutane / CH3 CH2 CH2 CH2Br Because it is a primary alkyl halide b) Because carbocation formed in SN1 reaction is sp2 hybridized and planar.

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16

1

.s

(i) Br2 / H2O or aq. Br2 (ii) LiAlH4 or NaBH4 or H2 / Ni (or any other) (iii) R – Cl and anhyd . Al Cl3 (iv) Acidic or alkaline KMnO4, K2Cr2 O7 (acidic) (i) Schottky defect, due to similar size of K+ and Cl- ion (ii) n-type (iii) CO2 (iv) Ferromagnetic a) (i) The fuel cell runs continuously as long as the reactants are supplied (ii) Highly efficient (iii) Pollution free (any two)

½x4=2

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19

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18

( where R = -CH3)

ch

oo

ls

.a

Or

20

b)

log Kc = log Kc =

nE 0 cell 0.059

2xE 0 cell 0.059

½ +½ 1 ½ ½ ½ ½ ½

2

AglaSem Schools

2xE 0 cell 0.059 0.059 = 0.0295 2

log 10 = E0cell = 21

V

→ SO2

SO2 Cl2 At t = 0s

½

[log 10 = 1]

0.4 atm

1

+

Cl2

0 atm

At t = 100s (0.4 – x) atm

0 atm

x atm

x atm

Pt = 0.4 – x + x + x

om

Pt = 0.4 + x 0.7 = 0.4 + x

2.303

k=

2.303

log 0.1

.a

x 0.6021 = 1.39 x 10-2 s-1

ls

= k p1/n or log (x/m)= log k + 1/n log p Dispersed phase = liquid Dispersion medium = Solid Because of coagulation of colloidal particles +3 +2 +4 oxidation states Transition elements (i) Form coloured compounds (ii) Form complexes (iii) Act as catalysts (iv) Paramagnetic (v) Form alloys (vi) Form interstitial compounds (any two) Or any other Zn, because of fully filled d orbitals OR a) Because of stable half filled orbitals (3d5) b) Because Zn has no unpaired electrons in d orbitals. c) Because of the presence of one unpaired electron in Ti3+ whereas there is no unpaired electron in Sc+3 A = CH3CN B = CH3CH2NH2 C = CH3CH2OH A = CH3 CONH2 B = CH3NH2 C = CH3NC Anomers – are the isomers which differ only in the configuration of hydroxyl group at C-1 of glucose Or

1 1 1 1 1 1

c)

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23

a) b) c) a) b)

0.4

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22

.

100

0.4

log 0.8-0.7

1

ch

k=

t

log

em

k=

t

as

2.303

gl

k=

.c

x = 0.3

23

24 25

(i) (ii) (i)

3

½+½ ½+½ 1 1 1 ½+½+½ ½+½+½ 1

AglaSem Schools

(ii) (iii)

27

(i) (ii) (iii)

(i) Concern towards environment / caring / socially aware / team work. (atleast

om

26

∝ and forms of glucose are called anomers Denaturation of proteins – when native protein is subjected to physical or chemical change, it loses its biological activity and is called denaturation. Essential amino acids are the amino acids required in our diet for the growth of the body / which are not synthesized by our body and obtained through diet. The drugs which are used to prevent the interaction of histamine with the receptors present in the stomach wall. Eg. Cimetidine / Ranitidine / Dimetapp (or any other) Chloramphenicol Because it is unstable at cooking temperature

two values)

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, Nylon -2-nylon- 6/ any natural polymer (iii) Homo polymer

Raoult’s law : state that for a solution containing volatile components, the partial vapour pressure of each component is directly proportional to its mole fraction. Ideal solution.

as

(i)

Wcacl

∆ Tb = i Kb xMcacl 2 x 2

1 1 1 ½+½ 1 1 1 1 1 1

Azeotrope is a liquid mixture which boils at constant temperature with constant composition. Osmotic pressure : is the pressure applied on the solution side to stop the flow of solvent across the semi permeable membrane from lower concentration of the solution to higher concentration. Colligative properties : are the properties of solution which depend upon the no of moles of solute or concentration of solute and not on the nature of solute. 1000 M= = x (B→ Solute)

1 1

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w

(ii)

½+½

OR

.s

a) (i)

1000 200 kg

x

w

28

ch

= 0.69K or 0.690C

oo

= 3x0.512 K kg mol-1x

ls

(ii)

.a

gl

28

1

.c

(ii) Polymers which can be degraded by the action of microorganisms. Eg. PHBV

1

(iii)

b)

V(L)

M=

29

.

V(

x

)

x 1.02

1 ½

½ 1 M = 1.02M a) (i) Because Bi is more stable in +3 oxidation state. (ii) Because of the availability to d orbital in P which is not in N/ nitrogen cannot extend its covalency beyond 4 (iii) Because of the formation of H2(g) which prevents the oxidation of Fe+2 to Fe+3 / 1x3=3 HCl is only a mild oxidising agent 4

AglaSem Schools

a) (i)

1+1

OR

a) (i)

1

om

29

(ii)

gl

ls

.a

Because of the presence of two unpaired electrons . Because of high ionization enthalpy of He. Because of the presence of two P-H bonds in H3PO2 whereas in H3PO3 one P-H bond is present.

CH3CH(OH)- CH3

1 1

1 1

b) (i) Add NaHCO3, benzoic acid will give brisk effervescence whereas ethyl benzoate will not give this test. (or any other test) (ii) Add tollen’s reagent , propanal will give silver mirror whereas Butan-2-one will not give this test. (or any other test) OR

1

w

Zn-Hg CH3-CH3 Conc HCl (iii) C6H5CHO + CH3-CHO dil NaOH C6H5CH(OH) CH2CHO (Award full marks even if only products are given)

w

(ii) CH3CHO

.s

ch

a) (i) CH3-CHO CH3MgBr CH3CH(CH3)- OMgBr H3O+

1

1

w

30

Polymeric

oo

b) (i) (ii) (iii)

1

as

em

.c

(ii)

5

1

AglaSem Schools

1 1 1

om

a) (i) Because the positve charge on carbonyl carbon of CH3 CHO decreases to a lesser extent due to one electron releasing (+I effect) CH3 group as compared to CH3 COCH3 (two electron releasing CH3 groups) and hence more reactive. (ii) because one of the –NH2 is involved in resonance with carbonyl group and hence acquires positive charge. (b) (i)

1

as

em

.c

(ii)

oo

ls

.a

gl

(iii)

w

w

.s

ch

(or any other suitable reaction)

w

30

1