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Combined Geo-Scientist (Main) SGSE-B-CMS
Examination, 2024
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 (QCA) Booklet
must be clearly struck off.
Answers must be written in ENGLISH only.
SGSE-B-CMS/68 1 [P-10.
1. (a)
()
(c)
(a)
(e)
(9)
(h)
(b)
(c)
3. (a)
(b)
(c)
SECTION—A
A weighing balance showed the weight of a substance 9:5 g, which is 0:5 g
lower than its actual weight. Calculate % relative error.
What do you mean by partition ratio (k’) and relative retention («) in
chromatography?
A4-00x10~* Msolution of aminobenzene in water has absorbance, A =0-504
at 280 nm in a 1-00 cm cell. What will be the transmittance of al-50x1073 M
solution of aminobenzene in water measured at the same wavelength but in
a 0°5 cm cell?
A thermogram of a magnesium compound showed a loss of 66:0 mg from
a total of 1265 mg used for the analysis. Identify the compound either as
MgO or MgCO3 or MgC,04. [Mg = 24-3, C=12, O=16]
What are the properties vital for detectors to be used in X-ray fluorescence
instrument?
How does plasma generate in inductively coupled plasma (ICP) technique?
What do you understand by the calorific value of a fuel?
Differentiate between AAS and ICP techniques based on the properties like
accuracy, interferences and detection limit.
What is Bonner affinity series in ion-exchange chromatography? Which factors
govern this series?
What is the role of monochromator in IR spectroscopy? Explain the types and
components of monochromator.
How does the furnace atmosphere affect the shape of the TG curve?
Specify at least two reasons. Compare the thermodecomposition profiles of
CaC,0,-H,0 taken in dry Oo(g) and in dry No).
What is X-ray diffraction qualitative phase analysis? How is it measured?
Mention its major applications.
What are the important components of inductively coupled plasma (ICP)?
Explain the functioning of sampler-skimmer system.
What do you mean by theoretical oxygen demand (ThOD)? Determine the
volume of the air needed for complete combustion of 1 m® of producer gas
having composition by volume Hy = 30%, CO=10%, CH, =4%, Ny =56%.
SGSE-B-CMS/68 2
10
10
10
10
10
10
4. (a) What is plate height (H)? Calculate the number of plates in the column
resulting in chromatographic peak with tp =52-3 sec and W,. =5-3 mm.
Also comment on the efficiency of the column.
2
Given : w=5-545{ tr ]
Wij2 10
(b) List out the interferences in flame photometry and describe the ways to
eliminate at least two of them. 10
(c) How are X-rays detected? Explain the various types of X-ray detectors. 10
5. (a) A set of seven measured values resulted in X =14-74(+0-38). Calculate
the confidence interval including the true value at a confidence level (CL)
of 99-:0%.
[Given : tg9.9 (degrees of freedom) : 4-604(4), 4:032(5), 3°707(6), 3:499(7)] 5
(b) (i) Calculate the wavelength of the resonance line of sodium atom, if the
excitation energy of the resonance level is 2:10 eV.
[Given : hc = 12330] 3)
(ii) 2:00 mL of the urine sample A was treated with reagent to generate
colour with phosphate, and the resulting content was diluted to 100 mL.
A second 2:00 mL sample B of the same urine was added to exactly 5:0 mL
of phosphate solution (0-°0300 mg/mL), which was treated in the same
way as the sample A. The absorbance of the solution from A =0-428,
and that from B=0-538. Calculate the concentration of phosphate
(mg/mL) in the urine sample A. 5
(c) (i) State the ultimate analysis of a fuel. Write the basic principle of the
method used for the analysis of nitrogen content in a fuel. 10
(ii) An ore sample of Fe30, weighing 1:3155 g was dissolved in HCl, and
treated with HNO; to convert all iron into Fe** state. The resulting
content was then diluted with water, followed by addition of NH3 (excess)
to precipitate Fe** into Fe (OH)3- Ppts were filtered, washed with water
and ignited to give the residue of pure FeO, weighing 0-°7273 g. Calculate
% w/w Fe3,0, in the ore sample.
[Fe,03 =159- 70, Fe30, =231-54] 5
SGSE-B-CMS/68 3 [ P.T.O.
SECTION—B
6. (a) Complete the following reaction and identify the products A and 8 :
0
( 8
Se >~
NH:
2
(b) Predict the product(s) of the following reaction. Which product will be major
and why?
CH
+HBr ——>?
( How will you prepare the compounds (7) and (11) from benzaldehyde using
suitable reagents?
CgHs—CH—COOH
NH OH
(1)
(0) Suggest the suitable starting materials and conditions to synthesize the
following compounds A and B :
COCH3
68: Cor
”
A B
(e) Give the product and mechanism of the following reaction :
AnH fi) ரான் ہی
(ii) NaBH4/MeOH
0 How will you synthesize the compounds 2 and Y from cyclohexanone by using
suitable reagents?
( ^ [
Y
x OH
SGSE-B-CMS/68 4
(g) Complete the following reactions and indicate how they are formed : 4
(h) An organic compound with molecular formula 01014 can exist in four
isomeric forms given below. The isomer that can be identified uniquely by
mass spectrometry is which one. Explain your answer : 4
& <.
(i) In the PMR () spectrum recorded at 293 K, an organic compound C3H7NO
exhibited signals at 6 7 - 8 (1H, 5), 28 (3H, 5) and 2-6 (3H, 5). Identify the
structure of the compound and explain your answer. 4
2 Arrange the following olefins in the correct order of IR stretching frequency of
C=C and explain your answer : 4
ADA
7. (a) Complete the following reactions and sketch a suitable mechanism for these
D
reactions : 5+5=10
0 + ૨૪-૫૩ ےت >?
0
0
i CH30Na-CH30H
(ii *
0
SGSE-B-CMS/68 5 [ P.T.O.
(b)
(0
(0)
()
(0
Explain the type of ring closure and the major product ) formed in the
following reaction : 5
. MeOOC—=—COOMe
+ ®
Complete the following reactions and give the mechanism for the conversion
of the step-2 product into the step-3 product : 5
CH3
~) (1)
|| + HCHO >? ` H > aNH2
Step-1 CH3—Cl Step-3
Step-2
Complete the following reactions and give the appropriate mechanisms : 5+5=10
೫೮೫೦೦೦೫
fi) /
"%==112
7 CgHsCO3H/CHCI.
(ii) [| >< 6Hs5CO3H/ 3 > .4 H®
6
() Complete the following reaction and explain the mechanism involved :
CHO
( ,
A
૦૦૦૪
(1) Complete the following reaction and provide suitable mechanism and
stereochemistry of the product :
1) BH3-THF
(1) BH3
6
5+5=10 01 )2(
Write the photochemical irradiation products of the following compounds : 5
8 2-pentanone
(i) trans-2,6-dimethylcyclohexanone
Predict the product of the following reaction and explain the mechanism
involved : 5
H2S04/H20
~ 3, Product
85 & CH;
SGSE-B-CMS/68 6
(d) Identify the products X and Y in the following reaction sequence. Explain the
mechanism of conversion of X to Y: 10
yA
CH3
6 O3/Me2S +x MeONa/MeOH |
Y
9. (a) An organic compound having C, H, N and X gave the following spectral data :
UV : Amax : 240 (€ 8000), 300 (£100) nm
IR : Vmax KBr : 3400, 3300, 3200 (w), 2900, 1620, 1600, 1500, 1380,
880, 820 cm™!
1H NMR: 6 7-20(1H, d J=9Hz), 6-50(1H, d J=3-5 Hz),
6-30 (1H, dd, J =9 Hz and 3:5 Hz),
3:50 (2H, broad s, removed on adding D0), 2:30 (3H, s)
Mass : m/z(RA) : 187 (90), 185 (90), 186 (20), 184 (20), 160 (10), 158 (10),
106 (100)
Find the structure of the compound and justify your answer. 10
(b) In the following reactions, identify the products A and B. Explain the
mechanism of formation of A : 5.
COOCH3 48% HBr
CH30Na/CH30H ry A fz
COOCH3 “
(c) (i) What is the concentration value for a solution of camphor (4, =14) in
hexane solution in a 10 cm cell? A at 295 nm was found to be 2:52.
(ii) Offer your explanation for the variation of A,,,, values for the following
compounds :
Methyl chloride Ama, =173 nm
Methyl bromide Ama, = 204 nm
Methyl iodide Amax = 258 nm 5
(a) Formulate the products and mechanisms of the following reactions : 5+5=10
Br
OOH
(i) Li/liq. NHs_,
CHO
0
(ii) cH=cu-Ucu, + -CH3ONa/CH3OH ,
SGSE-B-CMS/68 7 [ P:T.0;
10. (a) Predict the products C and D in the given reaction scheme [ (i) and (ii) ].
Provide the suitable mechanisms for both the reactions : 5+5=10
OCH;
6 CHBr3/KOH
i) || _CHBr3/KOH_ ~,
i
+ ( _ 250 * > p
675
(b) Find the structure of the organic compound with molecular formula 0140
which exhibited the following " NMR and 13 NMR spectral data. Justify
your answer : 5
1H NMR: 8 2:4 (8), 7:2 (, 9 = 8 Hz), 77 (, 7 = 8 Hz)
130 NMR: 5 21:0, 129-0, 130-0, 136:0, 141-0, 190-0
(c) Explain the following : 5
p-nitroaniline and anthracene both absorb near 375 nm but p-nitro-
aniline is yellow while anthracene is colourless.
8) Monomeric saturated aliphatic carboxylic acids show carbonyl stretching
frequency near 1760 1 while the saturated aliphatic ketones near
1720 .
(d) (i) Explain the mass spectral fragmentation of the following compounds
4 214 5 :
A B
8) An unknown organic compound with molecular formula 1 011914 gives
the following spectral data :
IR : 2210, 1724 .
ly NMR: 8 1-4 ( J=7-1Hz, उप्त), 44 (© J=7-1Hz, 21),
7-7 (©, J=7-0 Hz, 2H), 8:2 (©, J=7-0 Hz, 2H)
130 NMR: : 8 16, 62, 118, 119, 125, 126, 127, 168
Identify the structure and justify your answer. 10
® × ×
SGSE-B-CMS/68 8 SB24—288
