Organic Spectroscopy (H NMR) MCQs for CSIR NET, GATE - ChemContent

¹H NMR MCQ Questions
for CSIR UGC NET & GATE

Organic Spectroscopy
Topic wise Assignment-4

Quiz              PDF

Q1. An organic compound (C₇H₁₂O₂) exhibited the following data in the ¹H NMR spectrum.

[NET June 2011]

δ 7.10 (1H, dt, J= 16 Hz and 7.2 Hz), 5.90 (1H, dt, J= 16 Hz and 2 Hz), 4.1 (2H, q, J= 7.2 Hz), 2.10 (2H, m), 1.25 (3H, t, J= 7.2 Hz), 0.90 (3H, t, J= 7.2 Hz) ppm.
The compound, among the choices given below, is:

Q2. An organic compound (MF: C₈H₁₀O) exhibited the following ¹H NMR spectral data: δ 2.5 (3H, s), 3.8 (3H, s), 6.8 (2H, d, J= 8 Hz), 7.2 (2H, d, J= 8 Hz) ppm. The compound among the choices, is

[NET Dec 2011]

(a) 4-ethylphenol
(b) 2-ethylphenol
(c) 4-methylanisole
(d) 4-methylbenzyl alcohol

Q3. The NMR spectrum of AX₃ exhibits lines at δ = 2.1 and 2.3 ppm (for X type protons) and δ = 4.1, 4.3, 4.5, 4.7 ppm (for A type protons), measures from TMS with an instrument operating at 100 MHz. The chemical shift (in ppm) of A and X protons and coupling constant (in Hz) are respectively

[NET Dec 2011]

(a) 4.4, 2.2 and 20
(b) 2.2, 4.4 and 10
(c) 2.2, 4.4 and 5
(d) 4.3, 2.1 and 20

Q4. Appropriate H NMR chemical shifts (δ) for the protons A-D for the following compound are

[NET Dec 2011]

(a) A-6.8, B-5.7, C-3.9, D-2.1 ppm
(b) A-6.8, B-5.7, C-2.1, D-3.9 ppm
(c) A-5.7, B-6.8, C-3.9, D-2.1 ppm
(d) A-5.7, B-6.8, C-2.1, D-3.9 ppm

Q5. Compounds A and B exhibit two singlets, each in their ¹H NMR spectra. The expected chemical shifts are at δ

[NET June 2012]

(a) 6.9 and 2.1 for A, 7.7 and 3.9 for B
(b) 7.7 and 3.9 for A, 6.9 and 2.1 for B
(c) 6.9 and 3.9 for A, 7.7 and 2.1 for B
(d) 7.7 and 2.1 for A, 6.9 and 3.9 for B

Q6. In the 400 MHz instrument ¹H NMR spectrum, of organic compound exhibits a doublet. The two lines of the doublet are at δ 2.35 and 2.38 ppm. The coupling constant (J) value is

[NET June 2012]

(a) 3 Hz
(b) 6 Hz
(c) 9 Hz
(d) 12 Hz

Q7. ¹H NMR spectrum of HD would show

[NET Dec 2012]

(a) a singlet
(b) a doublet
(c) a triplet with intensity ratio 1:2:1
(d) a triplet with intensity ratio 1:1:1

Q8. In the ¹H NMR spectrum recorded at 293 K, an organic compound (C₃H₇NO), exhibited signals at δ 7.8 (1H, s), 2.8 (3H, s), 2.6 (3H, s). the compound is

[NET Dec 2012]

Q9. Correct statements regarding [18]-annulene are

[NET Dec 2012]

(A) It is aromatic
(B) The inner protons resonate at δ 9.28 in its 1H NMR spectrum
(C) There are six protons in the shielding zone
(a) A, B and C
(b) A and B
(c) B and C
(d) A and C

Q10. An AX system gave 4 lines at 4.72, 4.6, 1.12 and 1.0 ppm away from the TMS using an NMR spectrometer operating at 100 MHz. What are the values of J_AX (in Hz) and δ_AX (in ppm), respectively?
(NOTE: δ_AX= difference in the chemical shift values)

[NET June 2013]

(a) 12 and 3.6
(b) 6 and 3.6
(c) 12 and 2.86
(d) 6 and 2.86

Q11. An organic compound exhibits the following ¹H NMR spectra data

[NET June 2013]

δ 7.80 (2H, d, J= 8 Hz), 6.80 (2H, d, J= 8 Hz), 4.10 (2H, q, J= 7.2 Hz), 2.4 (3H, s), 1.25 (3H, t, J= 7.2 Hz)

Q12. An organic compound (C₆H₁₀O₂), which does not change the colour of ferric chloride solution, exhibited the following ¹H NMR spectral data:
δ 7.3 (1H, t, J= 8 Hz), 7.0 (1H, d, J= 8 Hz), 6.95 (1H, s), 6.9 (1H, d, J= 8 Hz), 5.3 (1H, broad s, D2O exchangeable), 4.6 (2H, s), 3.9 (3H, s).
Structure of the compound is

[NET Dec 2013]

Q13. The correct match of the ¹H NMR chemical shifts (δ) of the following species is

[NET June 2014]

(a) I-5.4, II-7.2, III-9.2
(b) I-9.2, II-7.2, III-5.4
(c) I-9.2, II-5.4, III-7.2
(d) I-7.2, II-9.2, III-5.4

Q14. The NMR spectrum of free benzene shows a peek at 7.2 ppm. The expected chemical shift (in ppm) of C₆H₆ ligand in ¹H NMR spectrum of [(n⁶-C₆H₆)Cr(CO)₃] and the reason for it, if an, is/are

[NET Dec 2014]

(a) 4.5, disruption of ring current
(b) 9.0, inductive effect
(c) 7.2
(d) 2.5, combination of inductive effect and disruption of ring current

Q15. The ¹H NMR spectrum of a dilute solution of a mixture of acetone and dichloromethane in CDCl₃ exhibits two singlets of 1:1 intensity. Molar ratio of acetone to dichloromethane in the solution is

[NET June 2015]

(a) 3:1
(b) 1:3
(c) 1:1
(d) 1:2

Q16. The number of chemical shift non-equivalent protons expected on ¹H NMR spectrum of α-pinene is

[NET Dec 2015]

(a) 7
(b) 8
(c) 9
(d) 10

Q17. The structure of the compounds that matches the ¹H NMR data given below is

[NET Dec 2015]

1H NMR (DMSO-d6): δ 7.75 (1H, dd, J= 8.8 Hz), 7.58 (1H, d, J= 2.4 Hz), 6.70 (1H, d, J= 8.8 Hz), 6.50 (2H, broad s), 3.80 (3H, s)

Q18. In the ¹H NMR spectrum of myrtenal, the two methyl groups are expected to display signals at (chemical shift δ values in ppm)

[NET June 2016]

(a) 1.35 (3H, s) and 5.0 (3H, s)
(b) 0.74 (3H, s) and 1.33 (3H, s)
(c) 1.22 (6H, s)
(d) 0.70 (6H, s)

Q19. In a 200 MHz NMR spectrometer, a molecule shows two doublets separated by 2 ppm. The observed coupling constant is 10 Hz. The separation between these two signals and the coupling constant in a 600 MHz spectrometer will be, respectively

[NET dec 2016]

(a) 600 Hz and 30 Hz
(b) 1200 Hz and 30 Hz
(c) 600 Hz and 10 Hz
(d) 1200 Hz and 10 Hz

Q20. ¹H NMR spectrum of an organic compound recorded on a 500 MHz spectrometer showed a quartet with line positions at 1759, 1753, 1747, 1741 Hz. Chemical shift (δ) and coupling constant (Hz) of the quartet are

[NET Dec 2016]

(a) 3.5 ppm and 6 Hz
(b) 3.5 ppm and 12 Hz
(c) 3.6 ppm and 6 Hz
(d) 3.6 ppm and 12 Hz

Ans Key:

1.a 2.c 3.a 4.d 5.a 6.d 7.d 8.a 9.d 10.a
11.a 12.b 13.a 14.a 15.b 16.d 17.b 18.b 19.d 20.a

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