Organic Chemistry Questions and Answers – Nuclear Magnetic Resonance – 2

1 In NMR spectroscopy, what is the product of Nuclear ‘g’ factor (gN), the nuclear magneton and the magnetic field strength (B0)?

A energy of transition from alpha to beta state

B chemical shift

C spin-spin coupling constant

D magnetogyric ratio

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Answer: energy of transition from alpha to beta state

2 An organic compound having the molecular formulae C₁₀H₁₄ exhibited two singlets in the ¹H NMR spectrum and three signals in the ¹³C NMR. What is the compound?

Organic Chemistry MCQ

A (a)

B (b)

C (c)

D (d)

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Answer: (a)

3 The ¹H NMR spectrum of a dilute solution of a mixture of acetone and dichloromethane in CDCl₃ exhibits two singlets of 1:1 intensity. What will be the molar ratio of acetone to dichloromethane in the solution?

A 3:1

B 1:3

C 1:1

D 1:2

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Answer: 1:3

4 What will be the strength of coupling between geminal protons in the following molecules?

Organic Chemistry MCQ

A Decrease as the size of ring increase

B Increase as the size of ring increase

C Remains same

D No relation between the size of the ring & coupling

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Answer: Increase as the size of ring increase

5 What is the value of gyramagnetic ratio of proton?

A 41.10 radian/Tesla

B 42.57 MHz/Tesla

C 26.75 radian/Tesla

D 41.10 MHz/Tesla

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Answer: 42.57 MHz/Tesla

6 What are the number of signals in ¹H NMR in the given molecules?

Organic Chemistry MCQ

A 3, 4, 4, 3 respectively

B 2, 6, 4, 2 respectively

C 2, 4, 6, 2 respectively

D 2, 4, 2, 6 respectively

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Answer: 2, 6, 4, 2 respectively

7 How many peaks are expected in low-resolution NMR spectrum of vinyl chloride and ethyl cyclopropane?

A 3,5

B 5,3

C 6,3

D 3,6

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Answer: 3,5

8 What will be the NMR frequency in MHz of bare ¹H in a magnetic field of intensity 1.4092 tesla (given g_N = 5.585 and μ_N = 5.05 x 10^-27 JT^-1)?

A 60 MHz

B 120 MHz

C 100 MHz

D 15 MHz

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Answer: 60 MHz

9 At room temperature, what is the number of singlet resonances observed in the 1H NMR spectrum of Me3CC(O)NMe2 (N, N-Dimethylpivalamide)?

A 3

B 4

C 5

D 2

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Answer: 3

10 An organic compound (MF; C₈H₁₀O) exhibited the following ¹H NMR special data: 62.5 (3H, s), 3.8 (314, s), 6.8 (2H, d, J 8 Hz), 7.2 (2H, d, J 8 Hz) ppm. What will be the compound among the choices?

A 4-ethylphenol

B 2-ethylphenol

C 4-methylanisole

D 4-methylbenzyl alcohol

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