jee-advance chemistry 2015 paper 2

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JEE ADVANCED 2015 CHEMISTRY (PAPER 2)

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SECTION - IThis section contains 8 questions. Each question, when workedout will result in one integer from 0 to 9 (both inclusive).1. Three moles of B2H6 are completely reacted with methanol.

The number of moles of boron containing product formed is2. The molar conductivity of a solution of a weak acid HX (0.01

M) is 10 times smaller than the molar conductivity of a solutionof a weak acid HY (0.10 M). If

– –0 0x yl » l

the difference in

their pKa values, pKa(HX) – pKa (HY), is (consider degree ofionization of both acids to be <<1)

3. A closed vessel with rigid walls contains 1 mol of 23892 U and

1 mol of air at 298 K. Considering complete decay of 23892 U to

20682 Pb, the ratio of the final pressure to the initial pressure of

the system at 298 K is4. In dilute aqueous H2SO4, the complex diaquodio-

xalatoferrate(II) is oxidized by MnO4 –. For this reaction, theratio of the rate of change of [H+] to the rate of change of[MnO4

–] is5. The number of hydroxyl group(s) in Q is

40 C

aqueous dilute KMnO (excess)Hheat P Q

+

°¾¾¾® ¾¾¾¾¾¾¾¾¾¾¾®

6. Among the following, the number of reaction(s) thatproduce(s) benzaldehyde is

I. 3

CO, HClAnhydrous AlCl /CuCl

¾¾¾¾¾¾¾¾®

II. 2H O100 C°¾¾¾®

III. 2

4

HPd BaSO-

¾¾¾¾¾®

IV. 2

DIBAL–HToluene,–78 CH O

°¾¾¾¾¾¾®

7. In the complex acetylbromidodicarbonylbis(triethylphosphine) iron (II), the number of Fe–C bond(s) is

8. Among the complex ions, [Co(NH2–CH2–CH2–NH2)2Cl2]+,[CrCl2(C2O4)2]3–, [Fe(H2O)4(OH)2]+, [Fe(NH3)2(CN)4]–,[Co(NH2–CH2–CH2–NH2)2(NH3)Cl]2+ and[Co(NH3)4(H2O)Cl]2+, the number of complex ion(s) thatshow(s) cis-trans isomerism is

SECTION - IIThis section contains 8 multiple choice questions. Each questionhas 4 choices (a), (b), (c) and (d) out of which ONE or MORETHAN ONE are correct.

9. The major product U in the following reactions is

CH CH–CH , H radical, initiator, O2 3 2high pressure, heat T

+=¾¾¾¾¾¾¾¾® ¾¾¾¾¾¾¾¾®

(a)

3

2


(b)

(c)

(d)

10. In the following reactions, the major product W is

NaNO , HCl20°C

OH

, NaOH

(a)N = N OH

(b)N = N

OH

(c)N = N

OH

(d) N = N

11. The correct statement(s) regarding, (i) HClO, (ii) HClO2,(iii) HClO3 and (iv) HClO4, is(are)(a) The number of Cl=O bonds in (ii) and (iii) together is

two

(b) The number of lone pairs of electrons on Cl in (ii) and(iii) together is three

(c) The hybridization of Cl in (iv) is sp3

(d) Amongst (i) to (iv), the strongest acid is (i)12. The pair(s) of ions where BOTH the ions are precipitated

upon passing H2S gas in presence of dilute HCl, is(are)(a) Ba2+, Zn2+ (b) Bi3+, Fe3+

(c) Cu2+, Pb2+ (d) Hg2+, Bi3+

13. Under hydrolytic conditions, the compounds used forpreparation of linear polymer and for chain termination,respectively, are(a) CH3SiCl3 and Si(CH3)4(b) (CH3)2SiCl2 and (CH3)3SiCl(c) (CH3)2SiCl2 and CH3SiCl3(d) SiCl4 and (CH3)3SiCl

14. When O2 is adsorbed on a metallic surface, electron transferoccurs from the metal to O2. The true statement(s) regardingthis adsorption is(are)(a) O2 is physisorbed(b) Heat is released

(c) Occupancy of *2rp of O2 is increased

(d) Bond length of O2 is increased15. One mole of a monoatomic real gas satisfies the equation

p(V – b) = RT where b is a constant. The relationship ofinteratomic potential V(r) and interatomic distance r for thegas is given by

(a)

(b)

(c)

3


(d)

16. In the following reactions, the product S is

(a)

(b)

(c)

(d)

SECTION - III

This section contains 2 paragraphs, each describing theory,experiments, data etc. four questions related to the two paragraphswith two questions on each paragraph. Each question has one ormore than one correct answer(s) among the four given options(a), (b), (c) and (d).

PARAGRAPH 1

When 100 mL of 1.0 M HCl was mixed with 100 mL of 1.0 M NaOHin an insulated beaker at constant pressure, a temperature increaseof 5.7 °C was measured for the beaker and its contents (Expt.1).Because the enthalpy of neutralization of a strong acid with astrong base is a constant (–57.0 kJ mol–1), this experiment couldbe used to measure the calorimeter constant. In a secondexperiment (Expt. 2), 100 mL of 2.0 M acetic acid (Ka = 2.0 × 10–5)was mixed with 100 mL of 1.0 M NaOH (under identical conditionsto Expt. 1) where a temperature rise of 5.6 °C was measured.

(Consider heat capacity of all solutions as 4.2 J g–1 K–1 and densityof all solutions as 1.0 g mL–1)

17. Enthalpy of dissociation (in kJ mol–1) of acetic acid obtainedfrom the Expt.2 is(a) 1.0 (b) 10.0(c) 24.5 (d) 51.4

18. The pH of the solution after Expt. 2 is(a) 2.8 (b) 4.7

(c) 5.0 (d) 7.0PARAGRAPH 2

In the following reactions

2 6

2 2 2

(i) B H48 6 8 8 (ii)H O , NaOH, H O

2

Pd BaSOC H C H X

H

-¾¾¾¾¾¾¾®

2+

(i) EtMgBr, H O(ii) H , heat

2

4 2 4

8 8

H O

HgSO ,H SO

C H O Y¾¾¾¾¾®

19. Compound X is

(a) (b)

(c) (d)

20. The major compound Y is

(a)

(b)

(c)

(d)

4


1. (6) 3B2H6 + 18CH3OH ® 6B(OCH3)3 + 18H22. (3) 1 ® HX 2 ® HY

( )m HX1

m°

la =

l

( )m HY2

m°

la =

l

12

a 1 1K C= a 22

a 2 2K C= a

= 0.01( )

( )2

m HX2

m°

l

l = 0.1

( )

( )2

m HY2

m°

l

l

\( )( )

( )( )

1

2

22a m mHX HX

2a m HYm HY

K 0.010.1

K 0.1

æ öl l= = ç ÷lè øl

= 0.121

10æ öç ÷è ø = 10–3

pKa(HX) – pKa(HY) = –log1

2

a

a

K

K = –log10–3 = 3

3. (9) Number of moles in gas phase, at start (ni) = 1238 206 4 092 82 2 –U Pb 8 He 6® + + b

Now number of moles in gas phase, after decomposition (nF)= 1 + 8 = 9 moleat constant temperature and pressure

F F

in in

P n 9 9P n 1

= = =

4. (8) 8H+ + 5[Fe(H2O)2(OX)2]2– + –4MnO ® Mn2+ +

+ 5 [Fe(H2O)2(OX)2]– + 4H2O

Rate = –4d[MnO ]1 d[H ] –

8 dt dt

+=

Hence, –4

rate of [H ]decay 8rate of [MnO ] decay

+=

5. (4) H

OH CH3CH3

H+

– H O2 +1, 2– Methyl Shift

+

D–H+

aq. diluteKMnO excess4

0°C

OH

OHOH

OH

6. (4)

CHO

CO, HClAnhyd AlCl /CuCl3

(Gatterman Koch Reaction)

CHCl 2H O2

100°C

CH

OH

– H O2

CHO

COClH 2

Pd–BaSO 4

CHO

COOMe CHODIBAL–H

Toluene, –78°C H O2

OH

(Rosenmund Reduction)

SOLUTIONS

5


7. (3)

Et P3 CO

Br–

CO

Fe+2

CH – C –3

O

Et P3

8. (6) All the complexes given show cis-trans isomerism [Co (NH2 — CH2 — CH2 — NH2) Cl2]

+ [CrCl2(C2O4)2]3–

[Fe(H2O)4(OH)2]+ [Fe(NH3)2(CN)4]

–

[Co(NH2–CH2–CH2–NH2)2(NH3)Cl]2+ (Co(NH3)4(H2O)Cl]2+

Co

ClNH3

en

enNH3

en

Cl

Co en

NH3HO2

Cl NH3

CoNH3

NH3NH3

H N3

H N3

NH3

OH2

Cl

Co

HO2

HO2 OH2

OH2

OH

OH

Fe FeHO2

HO2

OH2

OH

OH2

OH NH3HN3

HN3Fe

CN

CNCN

CN

NC

NC

NH3

CN

CNFe

en en

Cl

Co en

en

Co

ClCl

Cl

Crox

Cl

Crox ox

ox

ClCl

9. (b)High Pressure, heat

, H + Radical, initiator, O2

Cumene, T Cumene hydroperoxide, U

10. (a)NH2

–

11. (b, c)

(i) (ii) (iii) (iv)

Cl–O–H

O

ClOHO O OH

ClO OOH

Cl

O

Number of Cl = O bonds in (ii) and (iii) together is 3Number of lone pairs on Cl in (ii) and (iii) together is 3Hybridisation of Cl in all the four is sp3

Strongest acid is HClO4 (iv)

6


12. (c, d) Only group II cations precipitate as sulphide with H2Sin acidic medium that is (Cu2+, Pb2+) and (Hg2+, Bi3+)

13. (b) (CH3)2SiCl2 form linear polymer on hydrolysis and(CH3)3SiCl is a chain terminator.

14. (b, c, d) Reaction on metal surface

–

– –2 2

M M e

O e O

+¾¾® +

+ ¾¾®

This is an example of chemisorption.

15. (c) P(V–b) = RTÞ PV – Pb = RT

ÞPV Pb 1RT RT

= +

ÞPbZ 1RT

= +

Hence Z > 1 at all pressures.This means , repulsive tendencies will be dominantwhen interatomic distance are small.This means, interatomic potential is never negativebut becomes positive at small interatomic distances.

16. (a)(i) O3

(ii) Zn, H O2

NH3

–2H O2

17. (a) Let the heat capacity of insulated beaker be C.Mass of aqueous content in expt. 1 = (100 + 100) × 1= 200 gÞ ± Total heat capacity = (C + 200 × 4.2) J/K

Moles of acid, base neutralised in expt.1 = 0.1 × 1 = 0.1

Þ Heat released in expt. 1 = 0.1 × 57 = 5.7 KJ= 5.7 × 1000 J

Þ 5.7 × 1000 = (C + 200 × 4.2) × D´T.5.7 × 1000 = (C + 200 + 4.2) × 5.7

Þ (C + 200 × 4.2) = 1000In second experiment,nCH3COOH = 0.2, nNaOH = – 0.1

Total mass of aqueous content = 200 gÞ Total heat capacity = (C + 200 × 4.2) = 1000Þ Heat released = 1000 × 5.6 = 5600 J.

Overall, only 0.1 mol of CH3COOH undergoneutralization.

Þ DHneutralization of CH3COOH = –5600

0.1= – 56000 J/mol= – 56 KJ/mol.

Þ DHneutralization of CH3COOH = 57 – 56 = 1 KJ/mol18. (b) Final solution contain 0.1 mole of CH3COOH and

CH3COONa each.Hence it is a buffer solution.

pH = pKa 3

3

[CH COO ]log

[CH COOH]

-

= 5–log 2 + 0.1log 4.70.1

=

19. (c)i. B H2 6ii. H O , NaOH, H O2 22

OHPd-BaSO4

H2C H8 6

20. (d)

O

C H8 6

H O2

HgSO4

H SO2 4 i. Et MgBr, H O2

ii. H , Heat+

Y

,

jee-advance chemistry 2015 paper 2

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