Chapter 6 Multiple Choice Questions

* not completed

. In the context of electron ionization-mass spectrometry (EI-MS) of organic molecules, which of the following statements is most accurate?

The molecular ion and most fragment ions are even electron ions correct incorrect

The molecular ion is an odd electron ion, whereas most fragment ions are even electron ions correct incorrect

The molecular ion and most fragment ions are odd electron ions correct incorrect

The molecular ion is an even electron ion, whereas most fragment ions are odd electron ions correct incorrect

* not completed

. A molecule known to contain 3 nitrogen atoms is analysed by EI-MS. Which of the following statements arises from the nitrogen rule?

The molecular ion will have an even-numbered monoisotopic mass correct incorrect

All fragment ions will contain 3 nitrogen atoms correct incorrect

The molecular ion will have an odd-numbered monoisotopic mass correct incorrect

The molecular ion will be the base peak correct incorrect

* not completed

. Charge-mediated fragmentation, also known as inductive cleavage, i, is best described as:

fragmentation preceded by rearrangement of a group or groups in the ion correct incorrect

dissociation due to direct ionization of a σ-bond correct incorrect

homolytic fission of the bond between the atom adjacent to
the radical site and the atom two bonds away from the radical site correct incorrect

heterolytic cleavage of the bond adjacent to the charge site correct incorrect

* not completed

. α-cleavage is best described as:

fragmentation preceded by rearrangement of a group or groups in the ion correct incorrect

dissociation due to direct ionization of a σ-bond correct incorrect

homolytic fission of the bond between the atom adjacent to the radical site and the atom two bonds away from the radical site correct incorrect

heterolytic cleavage of the bond adjacent to the charge site correct incorrect

* not completed

. α-cleavage of the molecular ion of heptan-3-ol would lead to fragment ions at m/z:

59 and 87 correct incorrect

59 and 73 correct incorrect

43 and 101 correct incorrect

43 and 87 correct incorrect

* not completed

. Methyl esters give a characteristic McLafferty ion at m/z:

58 correct incorrect

72 correct incorrect

74 correct incorrect

88 correct incorrect

* not completed

. Fragmentation of protonated and deprotonated small molecules is characterised by:

loss of neutral molecules correct incorrect

loss of neutral radicals correct incorrect

loss of ions correct incorrect

loss of a proton correct incorrect

* not completed

. Fragmentation of positively-charged peptide ions by CID usually generates:

c and z ions correct incorrect

a and c ions correct incorrect

a and z ions correct incorrect

b and y ions correct incorrect

* not completed

. Fragmentation of multiply positively-charged peptide ions by ECD usually generates:

c and z ions correct incorrect

a and c ions correct incorrect

a and z ions correct incorrect

b and y ions correct incorrect

* not completed

. In the context of glycan MS/MS fragmentation, X ions are:

through-ring fragment ions that contain the terminal anomeric carbon end of the glycan correct incorrect

glycosidic bond fragment ions that contain the terminal anomeric carbon end of the glycan correct incorrect

through-ring fragment ions that contain the opposite end of the glycan to the terminal anomeric carbon correct incorrect

glycosidic bond fragment ions that contain the opposite end of the glycan to the terminal anomeric carbon correct incorrect