Infra-Red Spectroscopy (Organic Chemistry) MCQ Questions for CSIR UGC NET & GATE - Download PDF

IR Spectroscopy MCQ Questions
for CSIR UGC NET & GATE

Organic Spectroscopy
Topic wise Assignment-2

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Q1. Among the isomers of C₄H₆ given below, the compound which exhibits an absorption band at 3300 cm^-1 in the IR spectrum is

[GATE 2002]

(a) 1,3-butadiene
(b) 1-butyne
(c) 2-butyne
(d) cyclobutene

Q2. Match the following compounds P-S with their carbonyl frequencies (cm^-1) I-VI in IR spectroscopy.

[GATE 2004]

(a) P-IV, Q-III, R-I, S-VI
(b) P-III, Q-VI, R-V, S-II
(c) P-IV, Q-III, R-V, S-II
(d) P-II, Q-V, R-III, S-VI

Q3. Match the List-I compounds with their IR stretching frequencies in List-II

[GATE 2006]

(a) 1-iii, 2-iv, 3-i, 4-v
(b) 1-iii, 2-iv, 3-ii, 4-v
(c) 1-iv, 2-v, 3-ii, 4-i
(d) 1-iv, 2-iii, 3-v, 4-i

Q4. The IR stretching frequencies of the compound X are as follows:
3300-3500 cm^-1 (s, br); 3000 cm^-1 (m); 2225 cm^-1 (s); 1680 cm^-1 (s)

[GATE 2008]

Assign the values to the appropriate functional groups
(a) 3300-3500 = OH
3000 = CH
2225 = CN
1680 = CO
(b) 3300-3500 = CH
3000 = OH
2225 = CN
1680 = CO
(c) 3300-3500 = OH
3000 = CH
2225 = CO
1680 = CN
(d) 3300-3500 = CH
3000 = OH
2225 = CO
1680 = CN

Q5. The correct order of IR stretching frequencies of C=C bonds in the following olefins is

[GATE 2014]

(a) I > II > III
(b) II > III > I
(c) III > II > I
(d) III > I > II

Q6. In IR spectra, the stretching frequency (in cm^-1) of the carbonyl group in the following compounds is in the order

[NET Dec 2018]

(a) B > A > C
(b) A > C > B
(c) B > C > A
(d) C > B > A

Q7. In trans 1,2-dichloroethylene, the IR inactive mode is

[NET Dec 2019]

(a) C-Cl symmetric stretch
(b) C-Cl asymmetric stretch
(c) C-H asymmetric stretch
(d) In phase out of plane C-Cl bend

Q8. Among the following

[GATE 2020]

Total number of compounds showing characteristic carbonyl frequency less than 1700 cm^-1 in their IR spectra is ____

Q9. The strongest band observed in the IR spectrum of the final product of the following reaction appears, approximately, at ____ x 100 cm^-1. (up to one decimal place)

[GATE 2018]

Q10. In the IR spectrum recorded need a compound shows a strong and broad band at 3310 cm^-1. The band becomes sharp and shifts to 3600 cm^-1 when the spectrum is recorded in CCl₄ at high dilution. This proves that the compound has
(a) OH group, which is involved in intramolecular H-bonding.
(b) OH group, which is involved in intermolecular H-bonding.
(c) a terminal alkyne group.
(d) OH group, present in severely sterically hindered environment.

Ans Key:

1.b 2.c 3.c 4.a 5.c 6.c 7.a 8.[3] 9.[16.7 to 17.4] 10.b

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