Question 1

Which of the following statements about 13C NMR is not true?

Accepted Answer

A) "In 13C proton-decoupled NMR spectra,all peaks are singlets." 
B) "13C NMR spectra display peaks for only carbons that bear hydrogen atoms." 
C) "13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts." 
D) "13C NMR easily differentiates between the different hybridized carbons (sp3,sp2,and sp hybridized carbons)." 
A) "In 13C proton-decoupled NMR spectra,all peaks are singlets." 
B) "13C NMR spectra display peaks for only carbons that bear hydrogen atoms." 
C) "13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts." 
D) "13C NMR easily differentiates between the different hybridized carbons (sp3,sp2,and sp hybridized carbons)." B

Question 2

An unknown compound A has the molecular formula C7H14O2.Compound A absorbs strongly in the IR at 1700 cm-1.The 1H NMR spectral data for compound A are given below.What is the structure of compound A?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV C

Question 3

How many peaks would be observed for each of the circled protons in the compounds below?

Accepted Answer

A) I = 2; II = 6; III = 1 
B) I = 3; II = 5; III = 2 
C) I = 1; II = 5; III = 1 
D) I = 2; II = 6; III = 2 
A) I = 2; II = 6; III = 1 
B) I = 3; II = 5; III = 2 
C) I = 1; II = 5; III = 1 
D) I = 2; II = 6; III = 2 A

Question 4

How many peaks would be observed for each of the circled protons in the compounds below?

Accepted Answer

A) I = 8; II = 4; III = 3; IV = 3 
B) I = 7; II = 4; III = 3; IV = 4 
C) I = 7; II = 3; III = 3; IV = 3 
D) I = 7; II = 4; III = 2; IV = 4 
A) I = 8; II = 4; III = 3; IV = 3 
B) I = 7; II = 4; III = 3; IV = 4 
C) I = 7; II = 3; III = 3; IV = 3 
D) I = 7; II = 4; III = 2; IV = 4

Question 5

How many different kinds of protons are present in the following molecule?

Accepted Answer

A) 2 
B) 3 
C) 4 
D) 5 
A) 2 
B) 3 
C) 4 
D) 5

Question 6

How many different kinds of protons are present in each of the following compounds?

Accepted Answer

A) I = 6; II = 5; III = 3 
B) I = 7; II = 5; III = 3 
C) I = 7; II = 6; III = 3 
D) I = 6; II = 6; III = 3 
A) I = 6; II = 5; III = 3 
B) I = 7; II = 5; III = 3 
C) I = 7; II = 6; III = 3 
D) I = 6; II = 6; III = 3

Question 7

An unknown compound X has the molecular formula C10H11O2Br.Compound X shows a strong absorption in its IR spectrum at 1700 cm-1.The 1H NMR spectral data for compound X is given below.What is the structure of compound X?

Accepted Answer

A) Only I 
B) Only II 
C) Only III 
D) I or II 
A) Only I 
B) Only II 
C) Only III 
D) I or II

Question 8

An unknown compound has the formula of C9H12.The following 1H NMR peaks were observed: Doublet at Δ 1.22
Septet at Δ 2.83
Multiplet at Δ 7.09
From the data above,pick the compound below that fits the spectra data.

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 9

How many different kinds of protons are present in each of the following compounds?

Accepted Answer

A) I = 2; II = 3; III = 4 
B) I = 2; II = 3; III = 3 
C) I = 3; II = 3; III = 3 
D) I = 3; II = 3; III = 4 
A) I = 2; II = 3; III = 4 
B) I = 2; II = 3; III = 3 
C) I = 3; II = 3; III = 3 
D) I = 3; II = 3; III = 4

Question 10

What effect does increasing the operating frequency of a 1H NMR spectrum have on the value of chemical shift in Δ?

Accepted Answer

A) Chemical shift in Δ will also increase. 
B) Chemical shift in Δ will decrease. 
C) Chemical shift in Δ will remain the same. 
D) It is not possible to predict the change in chemical shift in Δ. 
A) Chemical shift in Δ will also increase. 
B) Chemical shift in Δ will decrease. 
C) Chemical shift in Δ will remain the same. 
D) It is not possible to predict the change in chemical shift in Δ.

Question 11

An unknown compound A has the molecular formula C12H16O.Compound A absorbs strongly in the IR at 1700 cm-1.The NMR spectral data for compound A are given below.What is the structure of compound A?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 12

Which of the following statements is true about electromagnetic radiation?

Accepted Answer

A) All molecules absorb electromagnetic radiation at some frequency. 
B) Frequency is directly proportional to wavelength. 
C) NMR uses the microwave region of the electromagnetic spectrum. 
D) The radio frequency region of the electromagnetic spectrum has the largest energy per photon. 
E) Energy is inversely proportional to frequency. 
A) All molecules absorb electromagnetic radiation at some frequency. 
B) Frequency is directly proportional to wavelength. 
C) NMR uses the microwave region of the electromagnetic spectrum. 
D) The radio frequency region of the electromagnetic spectrum has the largest energy per photon. 
E) Energy is inversely proportional to frequency.

Question 13

Which of the indicated protons would absorb furthest downfield in a 1H NMR spectrum?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 14

Which of the following spectroscopy methods does not involve the interaction of organic molecules with electromagnetic radiation?

Accepted Answer

A) Nuclear magnetic resonance 
B) Infrared spectroscopy 
C) Mass spectrometry 
D) Ultraviolet spectroscopy 
A) Nuclear magnetic resonance 
B) Infrared spectroscopy 
C) Mass spectrometry 
D) Ultraviolet spectroscopy

Question 15

Which of the following compounds does not show only one signal in its 1H NMR spectrum?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 16

How many different kinds of protons are present in each of the following compounds?

Accepted Answer

A) a: 5; b: 6 
B) a: 5; b: 5 
C) a: 4; b: 6 
D) a: 4; b: 5 
A) a: 5; b: 6 
B) a: 5; b: 5 
C) a: 4; b: 6 
D) a: 4; b: 5

Question 17

How many peaks would be observed for each of the circled protons in the compounds below?

Accepted Answer

A) I = 1; II = 4; III = 7 
B) I = 3; II = 3; III = 7 
C) I = 2; II = 4; III = 7 
D) I = 2; II = 4; III = 6 
A) I = 1; II = 4; III = 7 
B) I = 3; II = 3; III = 7 
C) I = 2; II = 4; III = 7 
D) I = 2; II = 4; III = 6

Question 18

Which of the labeled protons would absorb furthest downfield in a 1H NMR spectrum?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
A) I 
B) II 
C) III 
D) IV

Question 19

Which of the labeled protons absorbs furthest upfield in the 1H NMR spectrum?

Accepted Answer

A) HS1U1B1aS1U1B0 
B) HS1U1B1bS1U1B0 
C) HS1U1B1cS1U1B0 
D) HS1U1B1dS1U1B0 
A) HS1U1B1aS1U1B0 
B) HS1U1B1bS1U1B0 
C) HS1U1B1cS1U1B0 
D) HS1U1B1dS1U1B0

Question 20

What effect does increasing the operating frequency of a 1H NMR spectrum have on the frequency of an absorption in Hz?

Accepted Answer

A) Frequency of an absorption in Hz will also increase. 
B) Frequency of an absorption in Hz will decrease. 
C) Frequency of an absorption in Hz will remain the same. 
D) It is not possible to predict the change in frequency of an absorption in Hz. 
A) Frequency of an absorption in Hz will also increase. 
B) Frequency of an absorption in Hz will decrease. 
C) Frequency of an absorption in Hz will remain the same. 
D) It is not possible to predict the change in frequency of an absorption in Hz.

Exam 32: Spectroscopy C: Nuclear Magnetic Resonance Spectroscopy

Which of the following statements about 13C NMR is not true?

An unknown compound A has the molecular formula C7H14O2.Compound A absorbs strongly in the IR at 1700 cm-1.The 1H NMR spectral data for compound A are given below.What is the structure of compound A?

How many peaks would be observed for each of the circled protons in the compounds below?

How many peaks would be observed for each of the circled protons in the compounds below?

How many different kinds of protons are present in the following molecule?

How many different kinds of protons are present in each of the following compounds?

An unknown compound X has the molecular formula C10H11O2Br.Compound X shows a strong absorption in its IR spectrum at 1700 cm-1.The 1H NMR spectral data for compound X is given below.What is the structure of compound X?

An unknown compound has the formula of C9H12.The following 1H NMR peaks were observed: Doublet at Δ 1.22 Septet at Δ 2.83 Multiplet at Δ 7.09 From the data above,pick the compound below that fits the spectra data.

How many different kinds of protons are present in each of the following compounds?

What effect does increasing the operating frequency of a 1H NMR spectrum have on the value of chemical shift in Δ?

An unknown compound A has the molecular formula C12H16O.Compound A absorbs strongly in the IR at 1700 cm-1.The NMR spectral data for compound A are given below.What is the structure of compound A?

Which of the following statements is true about electromagnetic radiation?

Which of the indicated protons would absorb furthest downfield in a 1H NMR spectrum?

Which of the following spectroscopy methods does not involve the interaction of organic molecules with electromagnetic radiation?

Which of the following compounds does not show only one signal in its 1H NMR spectrum?

How many different kinds of protons are present in each of the following compounds?

How many peaks would be observed for each of the circled protons in the compounds below?

Which of the labeled protons would absorb furthest downfield in a 1H NMR spectrum?

Which of the labeled protons absorbs furthest upfield in the 1H NMR spectrum?

What effect does increasing the operating frequency of a 1H NMR spectrum have on the frequency of an absorption in Hz?

Structure and Bonding

Acids and Bases

Introduction to Organic Molecules and Functional Groups

Alkanes

Stereochemistry

Understanding Organic Reactions

Alkyl Halides and Nucleophilic Substitution

Alkyl Halides and Elimination Reactions

Alcohols,ethers,and Related Compounds

Alkenes and Addition Reactions

Alkynes and Synthesis

Oxidation and Reduction

Radical Reactions

Conjugation,resonance,and Dienes

Benzene and Aromatic Compounds

Reactions of Aromatic Compounds

Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction

Aldehydes and Ketones - Nucleophilic Addition

Carboxylic Acids and the Acidity of the O-H Bond

Carboxylic Acids and Their Derivatives Nucleophilic Acyl Substitution

Substitution Reactions of Carbonyl Compounds at the a Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond-Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Synthetic Polymers

Lipids

Spectroscopy A: Mass Spectrometry

Spectroscopy B: Infrared Spectroscopy

Filters

Which of the following statements about ¹³C NMR is not true?

An unknown compound A has the molecular formula C₇H₁₄O₂.Compound A absorbs strongly in the IR at 1700 cm^-1.The ¹H NMR spectral data for compound A are given below.What is the structure of compound A?

An unknown compound X has the molecular formula C₁₀H₁₁O₂Br.Compound X shows a strong absorption in its IR spectrum at 1700 cm^-1.The ¹H NMR spectral data for compound X is given below.What is the structure of compound X?

An unknown compound has the formula of C₉H₁₂.The following ¹H NMR peaks were observed: Doublet at Δ 1.22 Septet at Δ 2.83 Multiplet at Δ 7.09 From the data above,pick the compound below that fits the spectra data.

What effect does increasing the operating frequency of a ¹H NMR spectrum have on the value of chemical shift in Δ?

An unknown compound A has the molecular formula C₁₂H₁₆O.Compound A absorbs strongly in the IR at 1700 cm^-1.The NMR spectral data for compound A are given below.What is the structure of compound A?

Which of the indicated protons would absorb furthest downfield in a ¹H NMR spectrum?

Which of the following compounds does not show only one signal in its ¹H NMR spectrum?

Which of the labeled protons would absorb furthest downfield in a ¹H NMR spectrum?

Which of the labeled protons absorbs furthest upfield in the ¹H NMR spectrum?

What effect does increasing the operating frequency of a ¹H NMR spectrum have on the frequency of an absorption in Hz?