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Time Allowed : Three Hours
INDIAN FOREST SERVICE (MAIN)EXAM- 2023
CHEMISTRY
Paper - II
BJKE-B-CHM
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.
Questions No. 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.
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.
Answers must be written in ENGLISH only.
BJKE-B-CHM
SECTION A
Ql. (a) On the basis of Huckel’s Rules of aromaticity, identify the following
compounds as aromatic, antiaromatic and non-aromatic :
CH
ZN ios ei
ran) CHg (III)
dap
0 0
CH, CHg
(IV) (V)
(b) With the help of the isotopic labelling experiment, how will you establish
that B, 2 mechanism of ester hydrolysis involves true intermediate, not
a transition state ?
(c) | Complete the following reaction and identify the products A, B and C.
Br
p> i seo [Al
F Ph Ph
Ph Ph
A oO
C<———- B
(d) Compare with proper explanation, the solvolysis behaviour of the
following organic compounds :
Sag CHoBr IG CH,Br
CHg (CHg)3C
A B
BJKE-B-CHM 2
(e)
0
(g)
(h)
Q2. (a)
(b)
Complete the following reaction. Also indicate the name of the
mechanism involved in the formation of product(s).
00 ()
-------- `
Br Br
Explain why nucleophilic 1,2 shifts are more common than
1,2 electrophilic or free radical shifts. 5
Identify A and B in the following reaction : 5
OH
pee
190% டுவது
=
OH
Arrange the following aldehydes towards their ease of reactivity in
Cannizzaro’s reaction in the decreasing order : 5
N(CHg)o ०८७३ و0(
a 0) |
CHO CHO
I Il 111 IV
Cannizzaro’s reaction exhibits third order kinetic at low base
concentration and fourth order kinetic at higher base concentration.
Explain the mechanism of Cannizzaro in the light of above kinetic data. 10
Arrange the following molecules in the decreasing order of their
epoxidation tendency with reason(s) :
Lt Cl Ion Cl Cl
( OH CH, LO ‰„ OH
I 1 111
BJKE-B-CHM 3
(c)
(d)
Q3. (a)
(b)
(c)
(d)
Complete the following reaction with mechanism, giving the plausible
reasons for product spread : 10
OH
BFYOEt,
Give the product(s) of the condensation reaction of 2-butanone with
phenylhydrazine along with the mechanism. 10
Predict the product(s) of the following reaction. Which product will be
major and why ? 5
CH,
OC} HBr
Complete the following reactions :
OCH
_HNOs 3
OCH,
HNOs
Cl
Compare the rate of solvolysis in separate reactions of
(i) iodocyclopentane and (ii) 1-iodo-2,4-cyclopentadiene with silver
perchlorate in propionic acid. 5
Base catalysed bromination of optically active ketone results in
racemization of product. How will you account for this observation ? i)
BJKE-B-CHM 4
(e) Complete the following reaction with mechanism : 10
6૦૦૦૩85
9
+ OEt ?
68
(2 eq.)
(0 Complete the following reaction sequence by writing the structures of A,
B and C. Also write the name of the process involved. 10
Ce 1] A
| _>_- ¬ A= 5 0
H
Q4. (a) Complete the following reactions : 5
»)
“
Gi) Ph-CH=C=cH, ,
(b) 1 following compounds undergo elimination reaction in the presence
of டிவிடி at 55°C. Arrange them in decreasing order of
elimination behaviour rate. 5
= CH3CHBrCH;
I IV
(6) Indicating the product spread, complete the following pericyclic reaction: 5
CH 30 2
+ — `"
65
BJKE-B-CHM 5
(d) Butanal reacts with ethyl cyanoacetate in the presence of base. Give the
product(s) of this reaction along with mechanism. 5
(e) | Write the product(s) of the following reactions : 5
Ph. LOH
Ph OH
)
» OOO
OH
. NH, NaNO,/HCl
(ii) orc
(f) Predict the product(s) of the following reaction : 5
NgCH,COOC;Hs
;
(g) Write the product(s) of reaction of 1-chloro-3-phenyl-2-propanone and
1-chloro-1-phenyl-2-propanone CH3ONa/CH3OH separately. Explain the
mechanism involved. 10
BJKE-B-CHM 6
SECTION B
. (a) 145 the following groups of monomers in order of decreasing ability to
undergo anionic polymerization and give suitable justification. 5
CH = CH, CH = CH, CH = CH,
©) a | |
102 CHg OH;
(1) (111)
(b) Write the product for the following reaction and offer a suitable
explanation for your answer. 5
OH
(i) OsO,/Pyridine
120
Product
(6) Giving the mechanism complete the following reaction : 5
0
CHg
൫ Calculate ੭੭੩੬ Values of 2-methoxy-pent-3-en-2-one (A) and
3-methoxy-2-methyl-but-2-enal (3). 5
(e) Differentiate between o-xylene and p-xylene using IR spectroscopy. 5
(f) Identify the chemically equivalent protons and magnetically equivalent
protons in the following compound : 5
H
|
= H
BJKE-B-CHM
(g)
(h)
(a)
(b)
(c)
(d)
(e)
169)
From the data given below, calculate the mass of the parent peak (P)
whose daughter peak is 65.
MS (m/z) : 106, P, 65, 46-42, 29, 15
Write the structure of the complementary base pairs of DNA and show
their bonding interactions.
Complete the following reactions and give their mechanism :
Et,O/RT
@) CgH,-CH=CH-CHO + LiAIH, —2——>
Oo
cs SeO,
(ii) —>
Write the products in the following reactions with their mechanisms :
Ph Ph
Ph Ph
oO
fe)
hy
. .
a e ROH:
Two compounds having molecular formula C3Hg¢O react separately with
2,4-dinitrophenyl hydrazine to give blood red precipitates. Using IR
spectroscopy, how would you ascertain the functional group(s) present in
the compounds ?
What is coupling constant in 1H NMR spectroscopy ? How does external
magnetic field affect coupling constant values ? For two vicinal protons,
do we observe same or different coupling constant values and why ?
Which of the following two compounds will give higher intensity in
UV-Vis spectra and why ?
HC. H HC
C=C e Ne =O
a Yea, HC ~
(6) (ID
Write the effect of isotopic substitution on the rotational spectrum of a
diatomic molecule.
BJKE-B-CHM 8
5
5
10
10
Q7. (a)
(b)
(c)
(d)
(e)
()
(g)
(h)
Write the product(s) in the following photochemical reaction :
hv 9
COPh
Complete the following reactions sequence :
n-BuLi_ A CH = CH — CH = CHa
>
| ROH
Cc
Write the structure of neoprene and its monomer precursor which gives
Ph - CH = CH,
the former by use of Zeigler-Natta catalyst.
Why is the weight average molecular weight and the number average
molecular weight used in polymer chemistry rather than simply
measuring molecular weight ? Explain.
A compound having molecular formula C5HgO2g may be either ethyl
acrylate or vinyl propionate. How would you identify the correct
compound using IR spectroscopy ?
Give the mechanism for detection of N-terminal amino acid in a protein
with Sanger’s reagent.
A compound gives two signals at 5 4:3 ppm and 8 5-7 ppm. If the
spectrum is recorded in a 400 MHz NMR machine, write their chemical
shift difference in Hz (hertz).
A compound with molecular formula CgHg gives a product (CgHgO) upon
treatment with dil. sulphuric acid in the presence of mercurous
sulphate. Write approximate 1] NMR chemical shifts and multiplicity of
the protons in the product.
BJKE-B-CHM 9
Q8. (a) Complete the following reactions and give a suitable mechanism for both
the steps : 10
mCPBA/CHCl, _ . BF3 . Et20 _ B
>
(b) A compound having molecular formula CgHjo gives the following
MS (m/z) data :
m/z 120, 92, 91, 77 and 51
Write the mass fragmentation of the compound to elucidate the
structure of the fragment having mass m/z 92. 5
(c) Answer the following, when benzene is treated with an alkali metal in
THF as solvent : 5
(i) The spectroscopy to be used to identify the product.
(i) The structure of the product.
(iii) Total spin of the product.
(iv) The number of lines observed.
(v) The intensity distribution of the lines.
(d) A terpolymer is prepared from vinyl monomers A, B and C; the
molecular weight of the repeat units are 104, 184 and 128, respectively.
A particular polymerisation procedure yields a product with the
empirical formula A3.55 Bo.o9 Cy.99. Calculate the average unit weight
of the polymer. &
(e) | Acompound with molecular formula C5HgO3 gives the following data: 15
MS (m/z) 114, 76, 73, 60, 55
TR (em) 2981, 1850, 1758, 1250
1H-NMR (CDClg) § 2-43 (t, 4H), 1-96 (pent., 2H)
13C.NMR (CDCl) 8 177, 33, 19-6
Assign the structure to the compound.
BJKE-B-CHM 10
