CHEMESTRY PAPER 1 2001
Time Allowed: 3 hours Maximum Marks: 300
Candi dates should attempt Question Nos. 1 and 5 which are compulsory, and any three 0 f the remaining questions selecting at least one question from each Section. Assume suitable data if considered necessary and indicate the same clearly.

1. Answer any THREE 0 fthe following: (20x 60)
Nomialize the wave function
I1".1 . I

l.

Calculate the strength 0 f 0-0 bond from the following data
H20(g) 0(g)ilfu98= 926.98 kllmol
H20ig) ilH298= 1070. 6 kJImo 1



"W'hich 0 f the fo 110 wing are mo de stabl e Exp1ain:


F2 or FtJ+


He2 or He2+


N2 or
H2+ or H2­


Calculate the wavelength 0 f X-rays if the reflected angle for NaCl with density 2.163 gm per


cc. is 5.9 0
2. Calculate the energy sp acing between the first two levels if a particle of mass 10-21 gm is moving in a box oflength 10 cm.


Calculate the mean activity co effici ent of an aqueous solution of 0.001 mol ality 0 f BaCb at 25°C.




How is the standard potential EO of a half cell determined?



3. Show that the juncti on potential of a concentrati on cell is given by the equati on

KT,

F
Derive Clapeyron equation and show that it can be represented by the equation
U,H
p "" •
for liquid-vapour boundary assuming ideal gas behaviour and making certain approximations.

4. Show that the total differenti al 0 f entropy in terms 0 f temperature and vo1urne can be
expressed by the equation
C

J3 .. dr..




SECTION B
Answer any THREE of the followmg

(20x3=60)

The quantum efficiency for the destruction of a substance with 300 nm 11gbtlS 0.30 How much time Irradiation with 100 W source must continue to destroy one mole of the substance?


Write B.ET adsorption lSotherm equation. How is the volume Vm (the volume adsorbed when the solid surface lS completely covered by monolayers of the adsorbed gas) detenmned?


Comp ete the Valence bond and Molecular orbital theory


Describe the crystal structures of CsCI and CaF,


Show that the tetrahedral fiel d sp11tting is 0.444 times the 0 ctahedral fi eld splitting




Identify the less mtense band for each of the followmg patrs of electromc transitions and explatn the reason for the difference In mtensities


and


3A'g and 3A'g 3T'g





Draw the structures of the metal carbonyls gIVen below and


What product will be 0 btamed If is treated m the followmg ways?

NH3 and then by


NO,-and then NH3 The CellllS colourless m aqueous solution whereas the coloured. Explatn





Cyc1opentadine, molecule bonds as C,H" or Show the vanous modes of bonding 0 f!hi s mol ecul e gnllng example




Give the mechaniSm 0 f electron transfer reactions m Ferredoxm




Complete the followmg reactions m li qUid So, solvent


Kl


S03


Kl SOCl2
SbC!,



is the nonnal oXIdation state of lanthanides but and eXlst as the most stable species. Explam




(:SX.. ila.b}. JDDl

. .


RV



Time Allowed: 3 hours Maximum Marks: 300
Candi dates should attempt Question Nos. 1 and 5 which are compulsory, and any three 0 f the remaining questions selecting at least one question from each Section. Assume suitable data if considered necessary and indicate the same clearly.
1. Answer any three 0 f the fo 11 0 wi ng:
(20 x 3
lNhich of the following comp ounds are aromati c Give reasons to justify your
answer.
8H ........

II m
lV v
p Ka of cycloheptatrine is ab out 39 but that of cyclopentadiene is 16. Explain.
The triene can be readily deprotonated twice with a base to give a stable dianion In contrast to this, the neutral anal0 gue is quite unstab1e. Expl ain it.
Give stereochemistry of the pro duct that you would. exp ect from each of the following electro cyclic reactions:




(H.

l
I","r

l
Pro vi de mechanism for the fo 110wing re acti0ns (Dse "electron pushin arrows 0nly, do not
use words)




.....
.•1
...
0It
..
'L...... ........_

Formulate a mechanism for the depletion of atmo spheric ozone layer by CFC.
2. Givemech anism 0fthe followingre acti0ns:

(Dse"electron pushing' arrows only. do not use words)
/-......

PH t.J. ... l. .1-(OOi f
CJ
,_.......

o 2. tl G

I

II
/-·'··0




H
o
Explain the following:

"When ci s-2 -cWorocyc1 ohexanol is treated with a base, the product is cyc1ohexanone.


"Why does tins -1-bromo-4 -t-butyl cyc10hexane undergo E2 reaction in presence of GEt ion much more slowly than corresponding cis-isomer?



3. Predict the pro duct(s) 0fthe following reactions and give the mechanism of their formation


DMF'"
"
"

.RONO

IiI I-tA ..

...'
-iJ
"......., C

G "






:to
•
IldoI c... ••"
"

Which compound 1n the followmg pus will hydrolyse fasler


"

Outlme the mechamsm of fonnation of B from A m the folloWIng reactions

Q

•

"



Give the mechamsm 0f the followmg reaeli on










on II
H r



il Explain the following points about this condensation reaction: jiil (i)"W"hy is this condensation catalysed only by eN not by OH and GEt ions? jiil "W"hy do e1 ectronattracting substituents inhibit thi s condensati on? ji "W"hy do e1 ectronattracting substituentsinhibit thi scondensation?

H r

In principle one of the following Diels-JUder reactions could give two products, while the other must product only one. Explain ji H

0
II II
H H
il ji
il m ·le 7 ji

H r
v


SECnON B

5. Jl..nswer any three of the following:
(20 x
Givemechanism 0 fthe followingtrans formations:

(XNHoo:t

H IF oro r
H
il 00 Mg}EIhrir Q-OOH ji
OJ.l
H

H O MilO..




00
H .. .....)I



il ji


O}0
H 0"

f . t"


H0 r
OH



Explain the following:




Optically active cis-2, 3-elimethylcyc1obutane on reaction with eliazomethane yields an 0 ptically inactive mes 0 pro du ct.


Solvolysis 0 f optically active 3-phenyl-4-bromobutane in hot acetic aci d yi e1ds an optically inactive ester.


Give mechanism to account for the formation ofthe following product(s)
M. I
lWH..
A



I
1..JI!!lI!I !!1hIble MoN JIabk!l 25..
R.BH A
"" btiJrto group) " lllO'W.
"W'hen acetone is treated with a base, a higher boiling li quid .p. 130° can be isolated from there actionmixture. The spectral data 0 fthiscompoundare asfollows 1620,1695 UV; /...max 238 nm 11,700) 1H NMR; Owm 1.9 2.1 6.15
MS; rillI. (R.A.) De du ce the structure 0 f the co mpo und.
6. "W'hat i s sigmatropi c reacti on Illustrate and si gmatropic reacti ons.
"W'hy is thermal cyc1oaddition of 3-butadiene and ethylene easy but addition difficult?
E.xplain the foll owing ob servations:

Dravv structures be form ed in the foll owing reactions:




7. Drawstructures 0ftherepeating Wlits 0fthe fo110wingpolymericmateri als


Teflon


Tetylene


Nylon
Natural rubb er

The light catalysed reaction 0 f nitro syl chloride with cyclohexane gives an intermediate whi ch has an imp ortant role in the formation 0 f nylon 6. mat is the structure of this interme diate? Outline the furth erstepswhi chwould benecessary forthe ny10nsynth esis.




mat are nucl eotides and nucl eo sides? Draw the structure of a nucleotide.

men a nucleotide -cyclic adenylic acid) is treated with aqueous sodium hydroxide the or pro duct that is 0 btaind is, -adenylic acid (rather than 5'­adenylic acid). Gi ve an explanation to accoWlt for the preference to the cleavage 0 f Cs-oxygen bond in the hydrolysis.



Silk consists of whose polypeptide chains are made up of the repeating amino acid sequence: Gly-Ser-Gly-i.Ja-Gly-.fJa. mat characteristics of these amino acid side chains appearto favourthest ability 0 f -sheet structure?




Predict the mechanism of the following reactions



I·'
". ·1




....

8. The following dienes in ethanol have Amax.'s at 231 nm 21,000),236 nm 12,000). 245 nm
265 nm 6,400) and 282 nm Indicate which diene corresponds to whi ch sp ectrum.



"W"hich compound A or B is expected to show lower stretching frequency for C 0 group in the IR sp ectrum

How do trimeric phosphonitrillic halides comp are with b emene m structure and re activity?



A characteristic peak at rWz 58 is shown by 2-pentanone 86] in the mass spectrum. An isomer of this gives peaks at rWz 71 and 43, but not at mlz 58. "W"hat is the structure 0 f this compound? Another isomer of this gives peaks at rWz 86 and 57. Identify this isomer.




Sp eetral data of a comp ound (molecular formula C1H.S02) are given below. Suggest a structure to this comp ound which is consistent to the sp eetral data




UV; Amax. (etOH; 256 nm 324 nm


IR; 3175-3275 (broad). 1667 (strong), 1616, 1580, 1484, 1456, 1383, 1230, 1205, 11 51, 111 5 and 1029


IH NMR; (6ppmJ 10.83 which disapp ears on additi on 0 f 0 9.59
7.31 -6.79
Ms; m/z (Relative abundance): 122 121 93 29 (31