Question 1

In $^1$H NMR spectroscopy, what does the area under each signal (integration) represent?

Accepted Answer

The number of protons contributing to that signal

Question 2

A compound with molecular formula $C_4H_{10}O$ shows three $^1$H NMR signals with integration ratios of 3:2:1. Which of the following is the most likely structure?

Accepted Answer

sec-Butanol

Question 3

If a $^1$H NMR spectrum shows a triplet integrating to 3H and a quartet integrating to 2H, what is the most likely fragment present?

Accepted Answer

A methyl group adjacent to a methylene group

Question 4

Which of the following statements about $^1$H NMR splitting patterns is correct?

Accepted Answer

A proton with two equivalent neighboring protons will appear as a triplet

Question 5

A $^1$H NMR spectrum of an unknown compound shows a singlet integrating to 9H and a singlet integrating to 1H. Which structure is most consistent with this data?

Accepted Answer

tert-Butyl alcohol

Question 6

Given a $^1$H NMR spectrum with three signals: a doublet (3H), a quartet (2H), and a singlet (1H), which compound is most likely?

Accepted Answer

Ethyl acetate

Question 7

What is the expected splitting pattern for the methyl protons in ethyl bromide ($CH_3CH_2Br$)?

Accepted Answer

Triplet

Question 8

A molecule with formula $C_3H_8O$ shows two $^1$H NMR signals: a doublet (3H) and a septet (1H). Which structure fits this data?

Accepted Answer

Isopropanol

Question 9

Which of the following best explains why chemically equivalent protons give a single $^1$H NMR signal?

Accepted Answer

They are in the same chemical environment and experience the same magnetic field

Question 10

A $^1$H NMR spectrum of a compound shows a singlet at 2.1 ppm integrating to 3H. Which functional group is most likely present?

Accepted Answer

A methyl group attached to a carbonyl (acetyl group)

Question 11

If a $^1$H NMR spectrum shows two singlets, each integrating to 3H, which of the following compounds is most likely?

Accepted Answer

Dimethyl ether

Question 12

A $^1$H NMR spectrum of a compound with formula $C_2H_6O$ shows a triplet (3H) and a quartet (2H). What is the compound?

Accepted Answer

Ethanol

Question 13

Which of the following best describes the relationship between integration and the number of protons in $^1$H NMR?

Accepted Answer

Integration is directly proportional to the number of protons responsible for the signal

Question 14

A $^1$H NMR spectrum shows a singlet integrating to 6H and a quartet integrating to 2H. Which structure is most consistent with this data?

Accepted Answer

Ethyl methyl ether

Question 15

Which of the following is a correct step in determining the structure of an unknown compound using $^1$H NMR data?

Accepted Answer

Determine the number of different kinds of protons by counting the number of signals

Question 16

A $^1$H NMR spectrum of a compound shows a doublet integrating to 6H and a septet integrating to 1H. Which group is present?

Accepted Answer

Isopropyl group

Question 17

Which of the following best explains why a methyl group adjacent to a methylene group appears as a triplet in $^1$H NMR?

Accepted Answer

The methyl protons are split by two equivalent methylene protons

Question 18

A compound with formula $C_3H_8O$ shows a $^1$H NMR spectrum with a triplet (3H), a quartet (2H), and a broad singlet (1H). Which compound is this?

Accepted Answer

n-Propanol

Question 19

Which of the following is NOT a possible reason for observing a singlet in a $^1$H NMR spectrum?

Accepted Answer

The protons are split by two equivalent neighbors

Question 20

A $^1$H NMR spectrum of a compound shows a singlet at 3.3 ppm integrating to 3H. Which functional group is most likely present?

Accepted Answer

Methoxy group ($-OCH_3$)

Nuclear Magnetic Resonance Spectroscopy: Structure Determination Using ¹H NMR

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