IAS Mains Chemistry 2008

7/23/2019 IAS Mains Chemistry 2008

1/7

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1 ... .. .I

ll \ .':';.. \: ;J W S . f l : ) ,

;;

Time Allowed: 3 hours Maximum Marks :

3

Can

li

dates should attempt Question Nos. I and 5 which are compulsory, and any three of the remaining

questions selecting at least one question from each Section. Assume suitable data

if

considered necessary

and mclicate the same clearly

PA,I R

' U

SEC11 NA

I

Answer any three of the

follo1Mng

(a) (i) State and explam Heisenberg's uncertamtypnnc1ple Why

1s ot

phcable to large

part1cles

b)

c)

d)

(10)

(ii) When

an

electron was accelerated through a ..E2

'

ference of I.

00

0.0 I

kilovolt, what is the uncertainty ofposition of 7 e ' c l o n g its line ofproj ection?

(I 0)

of a chem1cal bond?

ow does the pnnaple of 'max1mum o v e r l a

Enumerate the essential cond1tton

What

1s

atonuc rad1us of a

cub1c

Ia : atom1c packmg factor m s1mple

system, body- centered

cub1c

syste t e r e d

cub1c

system

(20)

cubic

2.

a)

3.

4.

b)

b)

(20)

What are semi conductors ? Explain n - type and p-typ semiconductors. Discuss the effect of

temperature on semiconductors.

i)

Derive the Kelvin equation for the vapour pressure of droplets and bubbles.

(ii) What are nucleation centres? Indicate their importance.

(20)

(I 0)

(I 0)

c) Explain the criteria of equilibrium and spontaneity in terms of U, S, A and G.

(a) i)

(20)

The third law of thermodynamics states an impossibility. Justify this statement.

(I 0)

................................................................................................................................................................................................................................................................................................................................................

. ~ 1


2/7

5.

(ii) Explain why the molar entropy

of

ice crystals approaches 335 JIC

1

mor

1

, as the

temperature approaches zero kelvin.

(I 0)

b) Define chemical potential. Explain its significance. Deduce equations for the variation of

chemical potential with temperature and pressure.

c)

i)

(u)

(20)

What is the maximum number of phases that can be in equilibrium at constant

pressure and temperature in two- and three- component systems?

For the reaction

N2

(g)+ JH2 g) ~

2NH3

g)

Kp = I

64

x

10'

at

670

K Calculate ll.G

0

(I 0)

(a) Define activity, activity coefficient and mean activity coefficient

of

u t t o n

Denve and use the Debye-Huckel hm1t1ng

law

for mean activity

and mdicate how

it can be extended to more concentrated solution. 0.

b)

c)

d)

(20)

Denve an equation

to

relate temperature on rate d cal cui ate the energy

of

activation

1)

"Tetrahedral complexes

of

3d t r a n

O : _ ~

always

of

high

spm

J u s t i f y ~ ~

statement

(I

0)

(u) Calculate the crystal field s

1h

nergy and spm-only magnetic moment of

[V(H20)6f

1)

(I 0)

formation than lanthanides " Just

fy

the

6.

a)

b)

7

b)

(10 10 = 20)

d explain the law of photochemical equivalence. How are the discrepancies of this

explained?

(20)

What are heterogeneous catalysts ? Discuss the characteristics and mechanism of reaction on

heterogeneous catalysts.

i)

(20)

Identify one significant role m biological processes for each of the following

elements:

Fe,

Mg,

K, Zn, I

(I 0)

(ii) How is iron stored and transported in mammals? What is the oxidation state of iron

for storage and transfer?

(I

0)


3/7

(c) i)

(ii)

8 a) i)

b)

c)

The complex

[NiCI.t

is paramagnetic whereas [Ni CN).t

is

diamagnetic. Justify

the observations.

Explain the origin of pale pink colour of [Mn(H

2

0)

6

]

2

.

Explain the possible isomerism in the following complexes:

[Co(NH

3

)

5

Br]

SO

[Co(Nfu)sN02]

2

[Co(en)2Cl2]

(I 0)

(I 0)

(20)

(20)


4/7

' i ' r ~ \ ; ~ . ~ . \ : ~ ~ \ ~ ~ ~ ~ ~ . ; ~ . \ ~ ; ~ . ~ : : ~ \ . ; : ~ ~ ~ : ~ . : \ ~ ~ ~ \ ~ ~ ; ~ ~ \ ~ ; ~ m ~

l - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ r . ;

{

Time Allowed: hours Maximum Marks : 3

a)

b)

c)

2

a)

b)

i)

>

ii)

i)

ii)

2

x I

0 = 20)

A ~

.:a

8llld E

_..D

e ~

Ozonolysis

of

C:... a

B c

C: O

Where B D are stronger electron donor than A and

E)

pro duces four ozonides. Explain

mechanistically.

Butadiene on reaction with Br-F mole

ratio=

I: I produces two products. Explain.

20)

I

0)

L

~

l


5/7

3.

c) C

6

H

5

-Cl on reaction with NaOH in an autoclave produces phenol major), diphenyl ether and

p -phenyl phenol. Explain the mechanism of formation.

20)

d)

hy

p-nitro benzaldehyde does not follow benzoin condensation? Explain.

5)

e) C

6

H

5

CHO

is

refluxed

in

the presence of NaOH and excess HCHO. Write the major aromatic

product.

Identify the intermediates and pro ducts:

0

(a)

i)

C Hs -

CHO +

CH3C - CH3

base

Acid

CHz 0t)z

B

ltydrolylfis

) C

llaae

A

frl L

3--butadi.ene

excess)

+

e n z o q u i n o n e

(c) or,

A

heateri

Zn+-

atSO C

\rilhSe

5

add

AlCl,

--- --+A

Room temp.

5)


6/7

4.

Identify the products in the following reactions:

:H,-CB,-C -Oi:t

(a)

C l

2

-t::lr_-1-0I't

(.,

bl

c)

CHO

CliO

.,..,,_..,

J : ~ l

CN"

to

0 .

,_;

u; l

i)

(ii)

\ t f \

< . : ~ t o i l ) , ~

< ; l i ~ J

. OCN,

(il

HCI

----->-A ;>lJ

(ii)

TINO,

r iC

Hj)

i:J.ojJo :od kl W i J ( C ~

ON

following in their electronic

2 x I 0

=

20)

Explain the appearance of m/z = 44 peak in the mass spectrum of CH

3

CH

2

CH

2

CHO.

i

The dehydration of I, 2-dimethyl cyclohexanol (cis or trans) gives three alkenes. How

i

can you distinguish them on the basis of their IR spectra?

2 x

I 0

=

2

0)

(d) (i)

The

geometric isomers of stilbene show at 278 and 294 nm. Assign each value to i

appropriate isomer and sketch them.

i

i

~ ~ ~ > ~ : - ~ ~ - ~ ~ - ~ ~ - ~ ~ - ~ ~ ~ - - ~ ~ - : - ~ - ~ - ~ ~ ~ ~ - ~ : : : . ~ - ~ ~ = ~ : ~ .

- ~ ~ - - - J l


7/7

6.

7.

8.

h

H OH

2 x I 0= 20)

Identify A-D in the following

(a)

b)

c)

d)

(a)

b)

(c)

X 20)

(I 0)

(I 0)

How adipic acid can be produced from phenol (only

two

steps)? Q

2, 3-dimethyl-2-chlorobutane on E2 dehydrohalogenation gives ho y products? Can

they be distinguished by IR spectroscopy ? Justify your

+

Explain the mechanism o Hollowing transformation:

CJ

d i =0Y (j

..----

)

Whuhy

:sr.N NA

(ii) Mechanical.streng ylon is better than polyester. Explain.

(iii) Why o l l o w anti-Markovnikovs addition to

it

oscopy ? Give method for chemical separation of the

two

compounds.

(20)

(15)

(15)

(I

0)

(I 0)

(I 0)

(20)

w is azelaic acid obtained from oleic acid?

Azelaic acid HOOC(CH

2

)

1

COOH

Oleic

acid

CH

3

(CH

2

)

1

-CHCH(CH

2

)

1

COOH.

(I 0)

(c) A cyclonitrile can

be

polymerized

by

base catalyzed reaction but

not

by acid catalyzed

reaction. Explain.

d) In the mass spectrum of

CH

3

CH

2

C-OCH

3

the peaks

0

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IAS Mains Chemistry 2008