Deck 14: Mass Spectrometry

Question 1

Which of the following is not prominent in the mass spectrum of 2-methyl-2-butanol?

A) M - 29
B) M - 18
C) M - 15
D) M - 12

Answer 1

M - 12

Question 2

How many carbon atoms are present in a molecule which gives an M+1 peak that is 5.74% of the intensity of the molecular ion?

A) 5
B) 6
C) 11
D) 12

Answer 2

5

Question 3

In mass spectrometry, which of the following phrases is shortened to the acronym "FAB"?

A) flight averaged bumping
B) fast atom bombardment
C) fragmented atom beam
D) flying atom bashing

Answer 3

fast atom bombardment

Question 4

Which of the following corresponds to the molecular ion in EI mass spectrometry?

A) the most abundant ion
B) the ion with the smallest m/e
C) the ion formed by removal of an electron from the molecule
D) any ion formed by fragmentation of the molecule

Question 5

In mass spectrometry, which of the following phrases is shortened to the acronym "MALDI"?

A) mass analysis by light-detected ions
B) matrix assisted laser desorption ionization
C) many atom loss-detecting ionization
D) molecular and light detecting instrument

Question 6

What is the y-axis of a mass spectrum?

A) mass
B) energy
C) abundance
D) field strength

Question 7

How many carbon atoms are present in a molecule which gives an M+1 peak that is 11.48% of the intensity of the molecular ion?

A) 5
B) 6
C) 11
D) 12

Question 8

What is the principle that allows us to use mass spectrometry to determine the molecular weight of a compound?

A) higher molecular weight compounds are less volatile
B) higher molecular weight compounds are more dense
C) a beam of higher molecular weight cations is deflected less by a magnetic field
D) ions with higher molecular weight absorb higher frequencies of light

Question 9

What are the most common products of the fragmentation of a molecular ion?

A) two radicals
B) an anion and a cation
C) a radical and a cation
D) two cations

Question 10

Which of the following bonds of the octane radical cation is least subject to fragmentation?

A) i
B) ii
C) iii
D) iv

Question 11

In mass spectrometry, which of the following phrases is shortened to the acronym "EI"?

A) electron injection
B) electron impact
C) energy initiated
D) energy insertion

Question 12

What is the x-axis of a mass spectrum?

A) mass
B) mass/energy
C) mass/charge
D) charge

Question 13

What are products of the collision between high energy electrons and methane?

A) CH₄^{- x} + 2 e^-
B) CH₃^- + H^x
C) CH₄^+x + 2 e^-
D) CH₃^x + H⁺ + 2 e^-

Question 14

Which of the molecules gives rise to a molecular ion with an odd value of m/e?

A) C₆H₁₂O₂
B) C₇H₁₀ClN
C) C₈H₁₈N₂
D) C₈H₁₂

Question 15

Which of the following sets of molecular ions does an alkyl chloride possess?

A) two molecular ions in a 2:1 ratio separated by two mass units
B) two molecular ions in a 1:1 ratio separated by two mass units
C) three molecular ions in a 1:2:1 ratio separated by two mass units
D) two molecular ions in a 3:1 ratio separated by two mass units

Question 16

Which of the following sets of molecular ions does a dibromoalkane possess?

A) two molecular ions in a 2:1 ratio separated by two mass units
B) two molecular ions in a 1:1 ratio separated by two mass units
C) three molecular ions in a 1:2:1 ratio, separated by two mass units
D) two molecular ions in a 3:1 ratio separated by two mass units

Question 17

Which of the following is most consistent with a molecule having a molecular ion with m/e of 77?

A) the molecule contains bromine
B) the molecule contains nitrogen
C) the molecule is an alcohol
D) the molecule is a hydrocarbon

Question 18

Which of the following sets of molecular ions does an alkyl bromide possess?

A) two molecular ions in a 2:1 ratio separated by two mass units
B) two molecular ions in a 1:1 ratio separated by two mass units
C) three molecular ions in a 1:2:1 ratio separated by two mass units
D) two molecular ions in a 3:1 ratio separated by two mass units

Question 19

Which of the following is the definition of the base peak of a mass spectrum?

A) the peak corresponding to the most abundant ion
B) the peak corresponding to the ion with lowest m/e
C) the peak corresponding to the molecular ion peak
D) the peak corresponding to the ion arising to loss of a proton from the molecular ion

Question 20

Which of the molecules gives rise to a molecular ion with an odd value of m/e?

A) C₆H₁₂Cl₂
B) C₇H₁₀N₂
C) C₈H₁₃N
D) C₈H₁₄Br₂

Question 21

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of M - 31?

A) 2-methylhexanoic acid
B) methyl hexanoate
C) ethyl hexanoate
D) hexanoic acid

Question 22

What is the most likely molecular formula of a compound that has a molecular ion in the EI mass spectrum with m/z of 97 and an M+1 peak that is 6.6% of the intensity of the molecular ion peak?

Question 23

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 91?

A) 1-octene
B) 1-hexanamine, CH₃CH₂CH₂CH₂CH₂CH₂NH₂
C) benzene
D) ethylbenzene

Question 24

Which of the following does not give rise to a prominent M - 41 peak in the mass spectrum?

A) 1-hexene
B) 3-methyl-1-hexene
C) 4-methyl-1-hexene
D) 5-methyl-1-hexene

Question 25

What is the most likely molecular formula of a compound that has a molecular ion in the EI mass spectrum with m/z of 136, with a M+1 and M+2 peaks that are 4.4% and 49% of the intensity of the molecular ion peak, respectively.

Question 26

What is the most likely moleuclar formula of a compound (that contains only C, H and O) which has a molecular ion in the EI mass spectrum with m/z of 104 and an M+1 peak that is 5.5% of the intensity of the molecular ion peak?

Question 27

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 30?

A) 1-hexanamine, CH₃CH₂CH₂CH₂CH₂CH₂NH₂
B) 1,1-dimethyl-1-butanamine, CH₃CH₂CH₂C⁽CH₃⁾₂NH₂
C) 1-hexanol
D) hexanal

Question 28

What is the most likely moleuclar formula of a compound that has a molecular ion in the EI mass spectrum with m/z of 120, with a M+1 and M+2 peaks that are 6.6% and 24% of the intensity of the molecular ion peak, respectively.

Question 29

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 43?

A) 1-hexanol
B) 2-hexanol
C) hexanal
D) hexanoic acid

Question 30

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 41?

A) 1-hexene
B) 2-hexyne
C) 3-hexanol
D) 2-chlorohexane

Question 31

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 45?

A) 1-hexanol
B) 2-hexanol
C) hexanal
D) hexanoic acid

Question 32

Which of the following gives rise to a prominent M - 15 peak in the mass spectrum?

A) hexane
B) 1-chloropentane
C) 1-pentanol
D) 3-methylpentane

Question 33

Which of the following gives rise to a prominent peak in the mass spectrum with m/z of 60?

A) 1-hexanol
B) 2-hexanol
C) hexanal
D) hexanoic acid

Question 34

Which of the following gives rise to a prominent M - 18 peak in the mass spectrum?

A) hexane
B) 1-chloropentane
C) 1-pentanol
D) 3-methylpentane

Question 35

Which of the following gives rise to a prominent M - 18 peak in the mass spectrum?

A) cyclohexane
B) cyclohexene
C) 1-chlorocyclohexane
D) cyclohexanol

Question 36

Which of the following gives rise to a prominent M - 15 peak in the mass spectrum?

A) cyclopentane
B) cyclopentene
C) cyclopentanol
D) methylcyclopentane

Question 37

Which of the following gives rise to a prominent peak in the mass spectrum at m/z of 39?

A) 1-octyne
B) 4-octyne
C) 5-methyl-3-octyne
D) 2,2-dimethyl-3-heptyne

Question 38

Which of the following alcohols does not give a prominent M - 15 ion?

A) isopropyl alcohol
B) tert-butyl alcohol
C) 2-hexanol
D) 3-pentanol

Question 39

Which of the following is not prominent in the mass spectrum of 2-methyl-2-butanol?

A) M - 15
B) M - 18
C) M - 21
D) M - 29