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Examination-2025 BGSP-C-CMS
CHEMISTRY
Paper - III
Time Allowed : Three Hours Maximum Marks : 200
Question Paper Specific Instructions
Please read each of the following instructions carefully before attempting
questions:
There are TEN questions divided under TWO sections.
Candidate has to attempt SIX questions in all.
Question No. 1 in Section A and Question No. 6 in Section B are compulsory. Of the
remaining questions, candidates have to answer FOUR questions, choosing TWO from
each Section.
The number of marks carried by a question/part is indicated against it.
Neat sketches are to be drawn to illustrate answers, wherever required. These shall be
drawn in the space provided for answering the question itself.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Assume suitable data, if necessary, and indicate the same clearly.
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:
Answers must be written in ENGLISH only.
BGSP-C-CMS i}
Ql. (a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Q2. (a)
(nigh) eingio?-080 beridmod
SSBIOTRON A
From the following data, determine the mass of the sample that should
be analyzed to obtain sampling standard deviation of + 5%
Given Data
Relative standard
euinastiennnaiiead deviation (%)
0-1 15
1:5 6
9-2 2:5
Write the van Deemter equation and briefly discuss its significance.
How can concentration of a non-absorbing analyte be measured by
UV-vis spectrophotometry ?
Show the flame absorption profiles for magnesium and silver with
respect to flame height. Justify.
What happens in the thermogravimetric analysis for the following
conditions ?
(i) Higher furnace heating rate
Gi) Larger particle size of sample
(iii) For sample undergoing endothermic reaction
Explain the working principle of quadrupole mass analyzer in ICP-MS.
Briefly outline the gravimetric method for the estimation of nickel
content in steel sample.
The powder X-ray diffraction pattern (first order) of a metal is measured
with Cu — K, radiation source (A = 1539 A). Calculate the lattice
spacing of the material for diffraction measured at 20 = 60°.
In an HPLC measurement, a solute has a retention time of 21-0 min and
an unretained species is eluted in 1:0 min using a mobile phase
comprising 20% (vol by vol) methanol and 80% water. Determine the
composition of methanol and water to elute the solute corresponding to
retention factor 5-0.
Given :
(i) Polarity index of water is 10-2, methanol is 5-1;
Gi) log 2=0-301
BGSP-C-CMS 2
5
10
(b)
(c)
Q3. (a)
(b)
(c)
Q4. (a)
(b)
(c)
Q5. (a)
(b)
(c)
Briefly describe the principle involved in ion-exchange chromatography.
Arrange the retention time of Lit, Ag*t, Zn2*, and Co*+ for a strong acid
resin in an ion chromatograph. Give reasons for the sequence of
retention of these species. 9+6=15
The Fe content in an iron ore sample is analyzed at five different
laboratories using the same analytical method. The Fe contents are
given below as wt% :
60-5%, 61:5%, 685%, 52-0% and 62:5%
Using the Q-test, find if any of the above data is due to accidental error
and can be rejected. 5
Given : Qo; for five analysis is 0-710.
(i) | Why does AAS analysis of calcium in a phosphate buffer solution
give poor result ? Suggest a method to improve the determination
of calcium by AAS in the above solution.
(ii) Take an example to describe how protective agents improve AAS
analysis. 10+5=15
What is a two line correction method in AAS measurement ? 5
What is a Globar and how does it act as an IR source ? What is the
advantage of Globar as compared to Nernst Glower ? 10
Thermogravimetric analysis of a mixture of anhydrous CaCO, and CaO
recorded between 500°C and 900°C indicates a weight loss from
290:60 mg to 230°80 mg. Determine the percentage of CaCOg in the
mixture. 10
Given : Molecular weight of CaCOg is 100-1 mol g and CaO is
56-1 mol g“!.
What are the interferences in inductively coupled plasma mass
spectrometry ? How are they eliminated ? 10
Write the significance of ultimate analysis of coal. Describe the method
for estimation of ash content in coal sample. 10
Briefly outline the basic theory and instrumentation of energy dispersive
X-ray fluorescence spectroscopy. 64+9=15
How are aniline point, cloud point and pour point relevant in the
analysis of petroleum products ? 10
Describe the method for estimation of TiO, in bauxite. 5
BGSP-C-CMS 3
SECTION B
Q6. (a) Carbenes exist in singlet and triplet states. Which of the two states of
carbenes is non-stereospecific in its reaction with alkenes ? Explain why.
Predict the product/s formed in the following reaction :
No
Lo =’
ae,
—~ =z cis-2-butene
(b) The rate of addition of bromine to styrene (Ph — CH = CH) is greater
than propene (CH; — CH = CH,). Provide a suitable explanation with
mechanisms for both.
(c) The reaction of propanoic acid with HCl can form two possible products,
but only one is formed in major quantity. Write the structure of the two
products and give suitable explanation.
(d) Predict the product in the following reaction and propose mechanism for
the formation of the —_
NaOEt , ,
EtOH” :
(e) Predict the product in the following reaction with correct relative
stereochemistry. Also provide mechanism for the formation of the
product.
(i) BH./THF .
a of f
2 (ii) NaOH/H, 0,
CH,
BGSP-C-CMS u
(f) Predict the structure of the product and name the reaction.
fe)
— A
|)
THF, CgH,
(g) Given below are two examples of Diels-Alder reaction. Provide the
product in the first reaction and the reactants in the second reaction :
S fe)
(i) 7
O
i H
@ A+B > :
(h) How can you distinguish between the following pairs on the basis of
their IR spectra ?
COOH
oO
ZO
(ii) aid
(i) 2-Pentanone and 3-Pentanone are structural isomers. Only one of these
compounds exhibits McLafferty rearrangement in Mass spectrometry.
Identify the same and provide the McLafferty fragmentation for the
compound.
BGSP-C-CMS 5
(j) Compound A exhibits the following spectral data :
H-C=C-CH,-CG-H
N
CH3
A
1H NMR - 400 MHz (CDClz) : 6 2.5(s, 1H);
2.0(d, 2H);
1.7(m, 1H);
1.0(d, 6H);
183C NMR — 400 MHz (CDClg) : 6 80, 70, 40, 30, 20
Assign the peaks of protons and carbon in compound A and justify your
answer. 4
Q7z. (2 W@W p-cresol (A) reacts with chloroform in alkaline medium to give B
which on addition with HCN gives C. The latter on acidic
hydrolysis gives chiral carboxylic acid D. Identify A, B, C and D.
Name the reaction and give plausible mechanism for conversion of
A>B. 5
(ii) Identify ‘A’, ‘B’ and ‘C’ in the following sequence of reactions. Also
provide mechanism for conversion of ‘A’ to ‘B’. 5
O
|
“ (i) SOCI. C)H;OH
i
(ii) NaN3
(b) @ Following are examples of pericyclic reactions. Predict the
pathway (thermal/photochemical) and the mode of rotation
involved in each case. Also provide the HOMO involved, with
correct phase relationships, in both pathways. 5
Ph > SU Ph Ph
CE, 7+ OC, + CRT
Ph Z~™ ph “Dh
B A
BGSP-C-CMS 6
(ii) Study the following chemical transformation and _ propose
structure of A. Give the possible mechanism for the formation of
the product in the reaction. 5
—
Oo
ro
A (i) NaOH —
eee
Gi) H oH g a
() @ Predict the product and give mechanism for the formation of the
same in the reaction given below : 5
CHO
NaCN
PS 9
—— 7
C)H;0OH,
H,O
OCH3
Gi) Which of the following two Ketones X and Y will be more prone to
Norrish Type II reaction ? Give plausible mechanism and justify
your answer about the reactivity of X and Y. 5
O O
° Fit
4 CH; CHg
™
Qs. (a) (i) Rationalise that reacts with LiAlH, but E,C = CMe
| | 4 2 2
Cc
ZN
Me Me
does not. Justify the statement. 5
(ii) | What are ‘doped’ and ‘non-doped’ conducting polymers ? Provide
representative structures of “all-cis-polyacetylene” and
“all-trans-polyacetylene” polymers. 5
BGSP-C-CMS 7
©) In the following sequence of reactions, two compounds are formed,
‘A’ and 73. Predict the structures of A and . Also give possible
mechanism for the formation of ‘A’ from the starting material. 5
Br 9
||
“ (i) n-BuLi A R-C-O-O-H
(ii) Cyclohexanone ) [130
(ii) Predict the structures of ‘A’ and in the following reaction
sequence and give mechanism for formation of ‘B’ from ‘A’. 5
CH3
01) 00 EtOH
A
(€) (i) Complete the following reaction and identify A and B. Give
justification. 5
[~ `
200°C A 260°C B
(ii) ` Predict the product and propose mechanism for the formation of
the reaction given below :
9
a
9. ) (1 Complete the following reaction and sketch a suitable mechanism
for conversion of A > B. 5
CH,COOEt
NaOEt _ NaBH
CH,COOEt
A
BGSP-C-CMS 8
(ii) | What is the characteristic application of polyurethane polymers ?
Provide repeating unit formed by reaction between the following
monomers. 5
(b) W@W Complete the following reaction with suitable mechanism and
explanation for the products formed X and Y. 5
— 78°C +X
CH, = CH — CH = CHa + HBr
60°C Y
Gi) Predict the major product formed with correct stereochemistry in
the reaction given below. What is the role of t-butyl hydroperoxide
and Titanium tetraisopropoxide in the given reaction ? 5
t-BuOOH
| Ti(O-i-Pr), ;
OH (L)-(+)-Diethyl tartarate ~
CH,Cly, - 78°C
(c) Giving proper explanation, deduce the structure of the organic
compound with molecular formula CjgH,3;NO, having the following
spectral data : 10
IR, em! : 3300, 1600
1H NMR, 8 : 1:32 (t, 3H), 2°10 (S, 3H), 4:02 (q, J = 6 Hz, 2H),
6:8 (d, J = 8 Hz, 2H), 7-4 (d, J = 8 Hz, 2H),
7-9 (brs, 1H)
13C NMR,5 =: = 18, 26, 65, 118, 123, 131, 157, 169
Mass (m/z) : 179 (M+), 164, 136, 134
BGSP-C-CMS q
Ql0. (a) Wi Predict the product formed in the following reaction. Provide the
correct description for each step of the overall chemical
transformation.
07 NZ
a
ed
(ii) Predict the products P and Q and identify the concerted process
involved in the following reaction :
0
OWL”. CN : 3
CH30
0
(b) @ Two Ketones were filled in two reagent bottles A and B, but their
labels got damaged and were removed. Measurement of UV
spectra of the contents of the two bottles gave Ama, 249 for A and
287 nm for B. Assign the structures with appropriate Ay, for
A and B by using Woodward-Fieser rule.
@) fas %
Ci, COCH;
fe)
ea8)
BGSP-C-CMS 0
(ii)
(c) @
(ii)
BGSP-C-CMS
Find the structure of an organic compound having C, H and O
with molecular weight 108, which exhibited the following peaks in
the IR spectrum, cm~! : 3401, 3077 (w), 2899, 1499 (w), and 1456.
It can be oxidized with alkaline KMnO, and gives negative test
with FeCl, solution.
An organic compound with molecular formula CgHgO, gives
following spectral data :
IR : Broad band between 3000 and 2500 cm7!;
1680 cm-!
1H NMR : 5811-0(s, broad, 1H); 7-8 (d, 1H, J = 16-1 Hz);
7-55 — 7-40 (m, 5H); 6-5 (d, 1H, J = 16-1 Hz)
13C NMR : 173, 147, 134, 133, 131, 129, 128, 127, 117
Deduce the structure and interpret the spectral data.
Compounds given below have the same molecular formula
CgHj905. Only one of the two compounds gives m/z ions at
43, 91 and 108 as major ions. Identify the compound and justify
your answer by proposing suitable fragmentation ions for the
compound.
fe)
II
—To)
Ph ~CH, -O-C-CHg and Ph-C-0-C,Hs
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