$$\Delta E = h \nu = h \cdot 2 \cdot B_0$

Question 1

Which nuclei can be studied by NMR spectroscopy due to having an odd number of protons or neutrons?

Accepted Answer

$$^{1}H,\ ^{13}C,\ ^{15}N,\ ^{19}F,\ ^{31}P$$

Question 2

In pulsed Fourier transform (FT) NMR, what is held constant during the experiment?

Accepted Answer

The magnetic field

Question 3

What is the equation for the energy difference between the two spin states in NMR?

Accepted Answer

$$\Delta E = h 
u = h \cdot 2 \cdot B_0$

Question 4

Which compound would show only one singlet in its $$^1H $$NMR spectrum?

Accepted Answer

1,2-dichloroethane

Question 5

What does the integration of a signal in $$^1H $$NMR tell you?

Accepted Answer

The relative number of protons producing that signal

Question 6

Which of the following statements about chemical shift is correct?

Accepted Answer

Protons in electron-poor environments are deshielded and appear downfield

Question 7

What is the reference compound used in both $$^1H $$and $$^{13}C $$NMR spectroscopy?

Accepted Answer

Tetramethylsilane (TMS)

Question 8

If a proton has two equivalent neighboring protons, what splitting pattern will it show in $$^1H $$NMR?

Accepted Answer

Triplet

Question 9

Which of the following will increase the chemical shift (move the signal downfield) of a proton in $$^1H $$NMR?

Accepted Answer

Being near an electronegative atom

Question 10

What is the expected splitting pattern for the methylene protons in 1,3-bromopropane ($$Br-CH_2$-CH_2$-CH_2$-Br$$)?

Accepted Answer

Quintet

Question 11

Which type of proton appears at the highest frequency (largest chemical shift) in $$^1H $$NMR?

Accepted Answer

Methine ($$CH)$$

Question 12

Why do aromatic protons appear at higher frequencies in $$^1H $$NMR?

Accepted Answer

They sense a larger effective magnetic field due to magnetic anisotropy

Question 13

Which of the following is true about splitting in $$^1H $$NMR?

Accepted Answer

Splitting occurs only if protons are separated by no more than three bonds

Question 14

What is the chemical shift range for $$^{13}C $$NMR spectroscopy?

Accepted Answer

$$0-220$$\ ppm

Question 15

Which of the following carbon environments would appear furthest downfield in $$^{13}C $$NMR?

Accepted Answer

Carbonyl ($$C=O)$$

Question 16

A molecule has three sets of chemically equivalent protons. How many signals will its $$^1H $$NMR spectrum show?

Accepted Answer

Three

Question 17

Which of the following best describes the effect of electron withdrawal on the chemical shift of nearby hydrogens?

Accepted Answer

It causes the signal to appear at higher frequency (downfield)

Question 18

What is the splitting pattern for a proton with three non-equivalent neighboring protons?

Accepted Answer

Quartet

Question 19

Which of the following is NOT a factor that determines the number of signals in a $$^1H $$NMR spectrum?

Accepted Answer

Integration value

Question 20

Which of the following statements about $$^{13}C $$NMR is correct?

Accepted Answer

The number of signals reflects the number of different kinds of carbons in a compound

NMR Spectroscopy: Principles and Applications in Organic Chemistry

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