Question 1

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162,both of equal intensity.This compound contains

Accepted Answer

A) two chlorine atoms. 
B) one iodine atom. 
C) one bromine atom. 
D) two bromine atoms. 
A) two chlorine atoms. 
B) one iodine atom. 
C) one bromine atom. 
D) two bromine atoms. C

Question 2

A compound X has a molecular ion peak in its mass spectrum at m/z 136.What information does this tell us about X?

Accepted Answer

A) X has a molecular mass of 136. 
B) The molecular formula for X is C8H8O2. 
C) The empirical formula for X is C4H4O. 
D) Both A (X has a molecular mass of 136)and B (The molecular formula for X is C8H8O2)are true. 
E) Statements (X has a molecular mass of 136),(The molecular formula for X is C8H8O2),and (The empirical formula for X is C4H4O)are all true. 
A) X has a molecular mass of 136. 
B) The molecular formula for X is C8H8O2. 
C) The empirical formula for X is C4H4O. 
D) Both A (X has a molecular mass of 136)and B (The molecular formula for X is C8H8O2)are true. 
E) Statements (X has a molecular mass of 136),(The molecular formula for X is C8H8O2),and (The empirical formula for X is C4H4O)are all true. A

Question 3

What type of signal(s)would you observe in the mass and (or)infrared spectrum of the following compound?

Accepted Answer

A) A signal at 95 amu 
B) A signal at 94 amu 
C) Two signals at 95 and 94 amu 
D) A signal at 106 amu 
A) A signal at 95 amu 
B) A signal at 94 amu 
C) Two signals at 95 and 94 amu 
D) A signal at 106 amu A

Question 4

2,3-dimethylbutane gives a base fragment peak at m/z = 43.Which of the following is the most probable structure of the fragment ion?

Accepted Answer

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

Question 5

What is the molecular ion,m/z,for the following molecule?

Accepted Answer

A) 72 
B) 70 
C) 68 
D) 66 
A) 72 
B) 70 
C) 68 
D) 66

Question 6

Heptane,C7H16,would have which of the following fragments in its mass spectrum? m/z
I 29
II 43
III 57

Accepted Answer

A) I 
B) II 
C) III 
D) All of the choices are correct. 
A) I 
B) II 
C) III 
D) All of the choices are correct.

Question 7

Butane,C4H10,would have which of the following fragments in its mass spectrum? m/z
I 15
II 29
III 57

Accepted Answer

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

Question 8

In electron impact mass spectrometry (EIMS),what is being detected?

Accepted Answer

A) The molecular mass of the compound 
B) The molecular formula of the compound 
C) The mass to charge ratio of any ionic species 
D) The mass to charge ratio of any neutral species 
A) The molecular mass of the compound 
B) The molecular formula of the compound 
C) The mass to charge ratio of any ionic species 
D) The mass to charge ratio of any neutral species

Question 9

Hexane,C6H14,would have which of the following fragments in its mass spectrum? m/z
I 29
II 43
III 57

Accepted Answer

A) I 
B) II 
C) III 
D) All of the choices are correct. 
A) I 
B) II 
C) III 
D) All of the choices are correct.

Question 10

What is the molecular ion,m/z,for the following molecule?

Accepted Answer

A) 72 
B) 70 
C) 68 
D) 66 
A) 72 
B) 70 
C) 68 
D) 66

Question 11

Pentane,C5H12,would have which of the following fragments in its mass spectrum? m/z
II 29
III 43
IV 57

Accepted Answer

A) I 
B) II 
C) III 
D) All of the choices are correct. 
A) I 
B) II 
C) III 
D) All of the choices are correct.

Question 12

2,2-dimethylbutane gives a significant fragment peak at m/z = 57.Which of the following is the most probable structure of the fragment ion?

Accepted Answer

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

Question 13

What would be the molecular formula of rose oxide which contains C,H,and O and has two degrees of unsaturation and a molecular ion in its mass spectrum at m/z =154?

Accepted Answer

A) C10H18O 
B) C9H14O2 
C) C10H2O2 
D) C8H10O3 
A) C10H18O 
B) C9H14O2 
C) C10H2O2 
D) C8H10O3

Question 14

Which of the following alkanes gives a significant fragment peak at m/z = 57?

Accepted Answer

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

Question 15

What type of feature will be observed in the EI mass spectrum of chlorobenzene?

Accepted Answer

A) An absorption at 3100 cm-1 
B) A signal at 113 
C) A signal at 112 and a signal at 114 in a ratio of 3:1 
D) A signal at 112 and a signal at 114 in a ratio of 1:1 
A) An absorption at 3100 cm-1 
B) A signal at 113 
C) A signal at 112 and a signal at 114 in a ratio of 3:1 
D) A signal at 112 and a signal at 114 in a ratio of 1:1

Question 16

Which of the following statements about the base peak of a mass spectrum is always true?

Accepted Answer

A) The base peak corresponds to the molecular ion. 
B) The base peak corresponds to the most abundant ion. 
C) The base peak corresponds to the lowest m/z. 
D) None of these. 
A) The base peak corresponds to the molecular ion. 
B) The base peak corresponds to the most abundant ion. 
C) The base peak corresponds to the lowest m/z. 
D) None of these.

Question 17

What is the molecular ion,m/z,for the following molecule?

Accepted Answer

A) 72 
B) 70 
C) 68 
D) 66 
A) 72 
B) 70 
C) 68 
D) 66

Question 18

What is the molecular ion,m/z,for the following molecule?

Accepted Answer

A) 72 
B) 70 
C) 68 
D) 66 
A) 72 
B) 70 
C) 68 
D) 66

Question 19

In a typical mass spectrum,a smaller signal is observed at a mass 1 amu higher than the molecular ion peak.Why?

Accepted Answer

A) Due to small impurities in the sample 
B) Machine error 
C) Because a small percentage of the compound will have a carbon that is the isotope 13C instead of 12C 
D) Because of fragmentation 
A) Due to small impurities in the sample 
B) Machine error 
C) Because a small percentage of the compound will have a carbon that is the isotope 13C instead of 12C 
D) Because of fragmentation

Exam 30: Molecular Ion Peaks and Fragmentation Patterns

You observe a compound that exhibits a mass spectrum with peak at 160 and a peak at 162,both of equal intensity.This compound contains

A compound X has a molecular ion peak in its mass spectrum at m/z 136.What information does this tell us about X?

What type of signal(s)would you observe in the mass and (or)infrared spectrum of the following compound?

2,3-dimethylbutane gives a base fragment peak at m/z = 43.Which of the following is the most probable structure of the fragment ion?

What is the molecular ion,m/z,for the following molecule?

Heptane,C7H16,would have which of the following fragments in its mass spectrum? m/z I 29 II 43 III 57

Butane,C4H10,would have which of the following fragments in its mass spectrum? m/z I 15 II 29 III 57

In electron impact mass spectrometry (EIMS),what is being detected?

Hexane,C6H14,would have which of the following fragments in its mass spectrum? m/z I 29 II 43 III 57

What is the molecular ion,m/z,for the following molecule?

Pentane,C5H12,would have which of the following fragments in its mass spectrum? m/z II 29 III 43 IV 57

2,2-dimethylbutane gives a significant fragment peak at m/z = 57.Which of the following is the most probable structure of the fragment ion?

What would be the molecular formula of rose oxide which contains C,H,and O and has two degrees of unsaturation and a molecular ion in its mass spectrum at m/z =154?

Which of the following alkanes gives a significant fragment peak at m/z = 57?

What type of feature will be observed in the EI mass spectrum of chlorobenzene?

Which of the following statements about the base peak of a mass spectrum is always true?

What is the molecular ion,m/z,for the following molecule?

What is the molecular ion,m/z,for the following molecule?

In a typical mass spectrum,a smaller signal is observed at a mass 1 amu higher than the molecular ion peak.Why?

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

Analyzing Molecular Motion and Infrared Spectroscopy

Organic Spectroscopy Concepts

Filters

Heptane,C₇H₁₆,would have which of the following fragments in its mass spectrum? m/z I 29 II 43 III 57

Butane,C₄H₁₀,would have which of the following fragments in its mass spectrum? m/z I 15 II 29 III 57

Hexane,C₆H₁₄,would have which of the following fragments in its mass spectrum? m/z I 29 II 43 III 57

Pentane,C₅H₁₂,would have which of the following fragments in its mass spectrum? m/z II 29 III 43 IV 57