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indian Forest Service (Mtn ——
Examination, 2024
CHEMISTRY
PAPER—II
Time Allowed : Three Hours Maximum Marks : 200
QUESTION PAPER SPECIFIC INSTRUCTIONS
Please read each of the following instructions carefully
before attempting questions
There are EIGHT questions in all, out of which FIVE are to be attempted.
Question Nos. 1 and 5 are compulsory. Out of the remaining SIX questions, THREE are to be
attempted selecting at least ONE question from each of the two Sections A and B.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly. Any page or portion of the page left blank
in the Question-cum-Answer Booklet must be clearly struck off.
All questions carry equal marks. The number of marks carried by a question/part is indicated
against it.
Answers must be written in ENGLISH only.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Assume suitable data, if necessary, and indicate the same clearly.
Neat sketches may be drawn, wherever required.
JBNV-B-CHMY/42 1 [ P:?:0.
SECTION—A
1. (a) Which one of the following is aromatic? Justify your answer. Give names of the
given annulenes :
CO
1 11
(b) What is secondary kinetic isotope effect? Explain it using the reaction of HCN
with the following molecules :
0
८७३० ८७३० 1
1 1
(c) Comment on aromatic/non-aromatic/anti-aromatic behaviour of the following
compounds and justify your answer :
H
CH, - 1. OH
2 1
/ N -
H 0
] 1] 111 IV
() Predict the products [A], B and 2. Also give the reaction mechanism of the
following reaction sequence :
CH3
NaNH.
| 2 > [A]—> B+C
Z 1753 0)
(e) Giving mechanism, write down the product(s) in the following chemical
transformation :
વર ૦૫૦૦૦
JBNV-B-CHMY/42 2
(f) Identify A and B in the following reaction/rearrangement with mechanism :
Me
Brg A —NaOMe ,
c~ Et,0 MeOH
(g) How does migration of R" group involving photochemical [1,5] sigmatropic
rearrangement in the following compound proceed with inversion of
configuration? Explain :
(h) Give the products in the following reaction sequences :
—+
5 NH,NH2/t-BuOK
(i) CH;—CHBr—CH,—COCH,; ———————_> ?.
DMSO, Heat
a NH,—NH
(ii) R-~CO—CO—R ee
Alc. KOH, Glycol 5
2. (a) (i) Indicate the product(s) in the following reaction. What information is
obtained about the reaction mechanism from the product(s) observed?
OQ—CH,—CH=CH—C,H; Q—CH,—CH=CH—CH,
HC. CH, CH,0 CH;
(i) Predict the generation of reactive chemical species giving suitable
explanation in terms of thermodynamic/kinetic control in the following
chemical equations :
RK R ee
A
As ee"
JBNV-B-CHMY/42 3 [ P.T.O.
(b) Identify the products [A] and in the following reaction :
ண்டி 7
—> [4] -
3 5
(1) Arrange the following chemical entities in order of their decreasing
stability :
9 (1)
I II 111
5
8 Complete the following reaction and justify the formation of the major
product with emphasis on intermediate formed in situ :
H _ ೦೫೬೦೫,
?
H 5
1
() () Define Hofmann product. Explain the formation of the major product with
the help of Newman projection formulae by taking the example given
below :
H =+
| | (CHg)3COK
CH3,CH,—C H ¬, ?
970, 10
(1) Predict the major product and identify the reaction given below by giving
its name :
H
Me
AZ H 5
°
Me 5
3. (a) Complete the following reaction with detailed reaction mechanism :
9
w || 1) 81
N 2122003,
20 10
JBNV-B-CHMY/42 4
(b) Write the major product(s) of each of the following rearrangements with
justification :
0 ¢ Aq. oO,
iy 4 ( \=No _ SOC,
fi he CRSCOSH
fiv) 1)NaOH
2) 2H,O*
H»SO,
ora oe? 15
(c) () In the cycloaddition reaction of cyclopentadiene with maleic anhydride, the
endo product is preferred even though the endo product is less stable than
the exo product. Explain. 10
(ii) Write the product indicating stereochemistry when 2E, 4Z-hexadiene is
undergoing thermal as well as photochemical reaction. 5
4. (a) Complete the following reactions giving proper explanation for the formation of
products with their spread :
1) CH3MgBr
oP
2) H,0/H
1) tBuMgBr
2) H,0/H*
? 10
(b) Write the product of the reaction between cyclohexanone and diethyl succinate
in the presence of a strong base followed by treatment with aqueous acid. Also
give the mechanism of this transformation. 10
JBNV-B-CHMY/42 5 [P.-T:0.
(c) () Write the product(s) in the following reaction sequence along with the
mechanism :
CHO
KCN/EtOH
Ph—CHOH—COPh +
HO, Heat
OCH,
10
(ti) Identify the products A and B in the following reaction sequence. Also
write the mechanism of Step II :
CH,CH,—NH, Poel
CY RCOC , , S SB
Step I Step II 10
SECTION—B
5. (a) Calculate M,, for a polydispersed polymer having three fractions with
molecular weights and mass % as follows :
Molecular weight: 200000 50000 100000
Mass % 50 20 30
where M,, is average molecular weight of the polymer. 5
(b) What is the energy of the lowest vibrational level of the simple harmonic
oscillator? Justify your answer. 5
(c) Complete the following reactions :
OOH
H3Na/NH; (1)
: 3
()
t-BuOH
-78 °C
CH,
is Na/NH3 (I)
(i ——-—+? 5
(d) Draw the structure of a peptide bond giving the values of bond angles and
bond lengths. 5
JBNV-B-CHMY/42 6
(e) Indicating the major/minor product(s), complete the following reaction :
CH,
hy S
CH,CH,—CH—CH,—CHO ———> ?
(ff Distinguish between acetanilide and N-methyl benzamide on the basis of IR
spectroscopy. 5
(g) How can you identify the presence of (i) chlorine, (ii) bromine and (iti) both
chlorine and bromine atoms in the molecule based on the percentage intensity
of isotope peaks relative to the intensity of molecular ion peak? 5?
(h) Define spin labels. Write the name and structure of the most commonly used
spin label for macromolecules’ structure investigation. 5
6. (a) (i) Write the structures of the products formed in the following reactions :
ie a
CH3 H t-BuOOH
CHCHs geo,
(2) or a_i 5
t-BuOOH
(ii) Giving mechanism, complete the following reaction :
CH,
1) LiAlH.
Cp ———_ >? 5
2) H,0/OH
(b) (i) What is living polymer? Explain the reaction mechanism by taking
example of a reaction of monomer styrene with BuLi. 10
(ii) Give the representative structure of silicone. Comment on its stability. 5
(c) () Complete the following photochemical reaction giving the most probable
mechanism :
hv
ies —_—— >? 10
JBNV-B-CHMY/42 7 [ P.T.O.
(ii) Arrange the following compounds in order of their decreasing Norrish
type II potential. Give the proper reason for the order you have given :
° COCH,CH,CH, ‘ COCHCH,CH ; (COCH,CH,CH,
ci CHO CF;
ar
I Il Wl
0 5
oar
Hi
IV Vv
CH;
7. (a) Write the structures of the products in the following reaction sequences :
(7S Bal, p MeOMPievme og 5
°
S 2) H,0,/OH
CH,
BH3/A H,02
ii R >S
(ty) lig) NaOH 5
(b) (i) Give and compare the approximate values of A,,,, and € of 3-pentanone
and 3-penten-2-one due to m-" and n-n"* transitions. 10
(ii) Predict Aya, of the following molecules based on Woodward-Fieser rules :
(4 CO
Clr CO
5
(c) Identify the structure of a compound having molecular formula CgH)3NO, and
displaying the following spectral data :
IR: Vmax 2981cm7! and 1736 cm7!
lH NMR : 81-31 (t, 3H), 2:42 (s, 6H), 3-20 (s, 2H), 4-18 (q, 2H)
Explain the mass spectral fragmentation of the identified compound for
m/z 131, 116, 103, 86 and 84 peaks. 15
JBNV-B-CHMY/42 8
8. (a) (i) How can you distinguish the following compounds on the basis of
IR spectroscopy?
Cl H
xX Y
5
(ii) State which of the following molecules are infrared active :
CH30H, CH3NH,, CO,, CH,, CO 5
(b) Differentiate between benzyl alcohol and anisole on the basis of mass spectral
fragmentation. 10
(c) (i) Distinguish between (1) ethyl acetate and methyl propionate and
(2) 2-nitroacetophenone and 4-nitroacetophenone with reference to
number of signals, approximate chemical shift values and spin-spin
couplings (multiplicity) in their 1H NMR spectra. 10
(ii) Deduce the structure of the compound obtained by condensation of
benzaldehyde and acetone in the presence of a base based on the following
1H NMR spectral data :
§ 2:31 (s, 3H), 6°73 (d, 1H, J =16 Hz), 7:32-7:40 (m, 5H),
7-52 (d, 1H, J =16 Hz)
10
kkk
JBNV-B-CHMY/42 9 25SS—192
