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Transcript of IAS Mains Chemistry xx5
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8/10/2019 IAS Mains Chemistry xx5
1/36
S l
.
No
26
4
CS
MA
IN
)EX
A
M,
20
10
C
DT
N
K
D
I
A
CH
E
M
IS
TR
Y
Paper 1
I
ime
A
llow
ed
Thr
ee
o
u rs
I
l
M
ax i
m u
m
M
ark
s
3
l
I
NS
TR
U
CT
IO
N
S
Ea
ch
qu
est
ion
is
p
rin
te
d bo
th
in
Hi
nd
ia
nd
in
En
g l
ish
.
ns
we
rs
m
us
tbe
wr
itt
en
in
.
th
e
m
ed
ium
specified
in
the
dm ission
Certificate
is sued
to
yo
u, w
hic
h
m
us
t b
es ta
ted
cle
ar
ly
on t
he
c
ove
r
o f
.
t
he
a
nsw
er
-b
ook
in
the
sp
ac
e
p
rov
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ed
fo
r
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urp
os
e.
No
ma
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s
wil
l
be
g
ive
n f
or
t
he
a
nsw
e
rs
wri
tte
n
in
a
m
ed
iu
m
o
the
r
tha
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cif
ied
in t
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m is
s i
on
C
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cat
e.
C
an
did
at
es
s
hou
ld
a t
tem
pt
Qu
est
ion
No
s.
a nd
which
arecompulsory,
andany
th r
o
f th
e
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ai
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es
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sel
ect
ing
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o
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m
ea
ch
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tio
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he
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um
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ue
stio
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dic
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ed
' a
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d
o f
th
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tiO
n:
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mb
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nd
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Coordinate
diagrams,
Vherever required,
m
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-
8/10/2019 IAS Mains Chemistry xx5
17/36
SI. No.
262
I C DTN K DIB
CHEMISTRY
Paper
II
l nm Allowed : Tflree Hours Maximum Marks : 300j
INSTRUCTIONS
Each question
is
printed both
in
Hindi and
in
English.
Answers must be written
in
the
medium
specified in the Admission Certificate issued
to
you, which must be s t a t ~ d clearly on the
cover
o f the Clnswer-book in the space
provided
for the purpose. Jlfo marks
will
be
.given for the answers
written in
a medium
other. than thai
specified
in the Admission
Certificate.
Candidates should attempt Question Nos.
and 5
whick
are compulsory,
and
any
thr
o f
the
remaining questions
selecting
at
least
Olle question
from
each Section.
Assume
suitable data
i f
considered necessary
and indicate
the
same clearly.
The number o f marks carried
by
each
question is indicated at the end o f the
question.
Symbols
and
notations carry
usual meaning,
unless
otherwise
indicated.
~ : ~ i
Cf T
~ 4
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Section A
1 Answer
the
following : Ox6=60
t:
(a) Whether the following
compound
is aromatic,
non-aromatic or antiaromatic. Justify.
(b) In
the
reaction sequence
NHNH2
v .
+CH, C
2
H
5
) C O - -+ P )
BF,
(Q)
identify (P) and (Q) and -clearly show
isotopi-
cally labelled *N.
c)
Write the
major product X) o
the reaction
CH3(CHz)JCHCH3
CH30Na CzHsOH
(X)
I
F
.
(d) Write
the
major product
formed
on treatment
of
urea with
NaOBr.
Also write the
name of
the reaction
involved.
(e) Identify
intermediate
P) and product (Q) m
the
reaction
v
{P]
- Q]
C-DTN-K-DIB
2
(Contd.)
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..........
u
en
1. HJ>1ktfud 'd'a1
Rt
R< d
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f) A mixture
of
formaldehyde and p-methoxy
benzaldehyde
s treated with cone. KOH.
Write the products of reaction.
2.
a) Identify P) to S) in the
reaction
sequence
20
R)
KOH
ale.)
0
P)
H20
- - -- Q )
HCOOH
S}
H2/N i
2-3
atm
293
K
b) 2-Methyl-3-phenyl-2,3-butanediol
on
treatment
with H
S0
4
gives
a
major product X).
Identify
X) and write
a
mechanism to explain
its
formation.
Also
write
the
name
of reaction
involved. 20
c) Draw resonating
structures for
the
attack
of
S0
H+ at different
positions of Indole, ~ s i n
curved
arrows.
At
which position attack occurs
preferentially
? Draw
an energy profile
diagram
for the position of preferential attack.
20
C-DTN-K-DIB
4
Contd.)
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~ )
' h R i ' l ' ' r n ~ ~ om p - . . r l < i l < f f i 1 6 l i 1 ~ & ~ : s 1 ~ t ~ ~
fil 'fOI
Cf>f
~ KOH ~ -d4 '11fll1.
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3. a)
Answer
the following : 15
.
i)
A student carried out reaction of aniline
with concentrated
H N O ~ S
Write
the structure
of
product/s he is
likely
to
obtain.
ii) Write
a
mechanism
to
explain
the forma
. tion of
major
product in i).
iii)
I f the reaction in {i) is carried out
only
in
. nitric acid,
write
an equation for the
formation of No;.
b)
Identify P)
to R) in
the
following:-
15
P)
i) OCH3
ii)
H20 /H
OH
H C;Q
COCH3
Q)
c) Write
the
resonance
structures
following:
. + /C H = C 0
H c.
N ~
[ .
~ N O
R)
of the
15
Explain
its
aromaticity
in
nitration reaction.
C-DTN-K-DIB
6
Contd.)
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-
' .
3 (ar) f . t A ~ M a ~ :att ~ (R) f q l q ~ " t A t : t : 15
(P)
-
(i) OCH
3
(ii) H20 /H
OH
c ~ .
anh.AICI
3
COCH
3
C-DTN-K-DIB
7
(Q)
R)
(Contd.)
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C-DTN-K-DIB
Contd.)
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8/10/2019 IAS Mains Chemistry xx5
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ii)
iii)
HCI
peroxide
(
P)
CCI
4
CH
3
CH
=
CH2 ~ . .
peroxide
Q)
trans-2-butene
Br
2
[RJ-< S)
T)
4.
(ar)
H ' ' R l f t < ~ d
~ < f i r
fst;q,
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Section B
5. Answer the
following
:
I0x6=60
(a)
Draw the
structure
present
in
DNA.
of
purine nucleotides
(b) Benzoic acid on reduction
with Na
in
liq
NH
3
gives 1,2-dihydroproduct, whereas, anisole
gives
2,5-dihydroproduct.
Explain.
(c) Predict
the
products and
explain the ir forma
tion
v
_c_H..:;3_c_o_c_H...:3; ..
A
v
(d)
What
chariges
do
you expect in the
electronic
spectrum of acetoacetic ester
in
hexane and
ether.
(e)
(f)
1
H
NMR
spectrum
recorded
for
CH
3
-CH=
CH
2
at
90
MHz
gave coupling constant (J) o f
5 Hz
for vinyl
protons.
If
spectrum
is
recorded
at
500 MHz,
write the expected value of co Jpiing
constant.
.
What
is the range of fingerprint region in infra
red spectrum.
Write the range in
which
.
.
carbonyl
group
normally absorbs.
C-DTN-K-DIB
10
(Contd.)
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8/10/2019 IAS Mains Chemistry xx5
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10x
6=6
0
m
1:1;
i
R ~
'"i
1"'
9f
\l'q
o1 1
1Ha
+w r
G ld
l'4l l
1
(
)
31
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li. a)
i)
Define
thennoplast
and
Which are thennoplast
following?
PVC
Phenolics
Aminoresins
Polypropylene
Teflon
Nylan
PoIyster
Polystyrene
thermosets.
among the
Alkyd
resin
Polyethylene
ii) Differentiate between LDPE
and HDPE.
10+5=15
b)
Give the synthetic route of epoxy resin based
on
bisphenoi-A. Mention
the
principal fields of
applications of epoxy resins. 5
c)
Write the product formed in
quinoline
by
C r0
3
the oxidation of
10
d) Identify and B and discuss the
selectivity
of
the
reagents 2xl0=20
C-DTN-K-DIB
12
Contd.)
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6. (ar) i ) ffl'f ~ ~ 4
t im. ffi ' f f i T ~
4 \ l N \ ~ 1
f . s 1 0 i 1 P I R < t ~
it i t
ffl 'f
~ l ~ < t ~ i t
?
. Rti 11 Pl'ffi .
Q;flt;;i'uM"'
q
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7. a) Write the structures of possible
products
of
following
photochemical
reactions and
mention the
type
of
Norrish process
I or II) in
each.
15
i)
v
ii)
v
CH CH2
-
C .
CH2CH2CHCH
---
. I
. CH
3
b)
Photochemical 2 2)
addition
of
benzophe
none with cis-
and
t r a n s ~ 2 b u t e n e
yield
a
mixture of same products. Explain their
formation
with the
mechanism.
15
{c)
Which among
the following. A or
B)is
formed
when Pent-2-ene
is
oxidised by
s
4
and
NaHS0
3
? Explain its formation with the
mechanism. 10
CH
2
CH
3
I
CH2CH3
I
H C O I 1
H-C-OH
I
I
H --c -
OH
HO-C-H
I
I
CH
3
CH
A)
B)
C-DTN-K-DIB
14
Contd.)
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7 .
(ar) f.h="'MMd Yii>l' lRetl H'f i ~ B > u m
i
( 'dit
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d) Identify
the compound susceptible for
oxidation and justify
i)
CH3
I
CHNH,
l
CH,OH
i i )
e) Write the reagents required for the following
conversions. 10
i)
0
0
0
0
0
ii)
CH3
CHO
CH
1
CHO
C DTN K DIB
16
Contd.)
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(G )
41P1Cfl
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8. (a) An organic compound with molecular
formula
C
9
H
10
gives
following
spectral characteristics
(b)
c)
(d)
Electronic
: Amax
at 235
nm
spectrum
Infrared
spectrum
NMR
spectrum.
Mass
spectrum
3035;
3000,
2925, 1640, 990,
915, 740
and 615
cm-1
at 31(2H), 48(IH),
51(1H),
58(1H),
71(5H)
m/e
at 117
Suggest
possible
structure with
probable
justification for
each
spectral feature.
30
What characteristic bands.
will be observed in
the
r
spectrum of
J,phenylethanone?
10
Room temperature NMR spectrum of
acetylacetone
exhibits two close
by
peaks at
=
197
and 214 ppm. Explain the reason
for their origin. What
other
peaks will be
observed. 10
How would you determine molecular
wt of
acetone
on the
,basis
of
its
mass spectrum
?
Suggest possible fragmentation pattern.
10
C-DTN-K-DIB 18
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s (ar) )
?
1 4 < . . ~ 6 ' 1 Slru'll'i
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IC
DT
NK
DIB
I
T
d
i'i lt.. ' l
:
ifd
J f
f- [f
R