Mass Spec Practice Problems (33 QUESTIONS AND ANSWERS).

Mass Spec
Practice
Problems (33
QUESTIONS AND
ANSWERS)
Which of the following molecular changes is necessary for
mass spectrometry to occur?
A) excitation of an electron from the ground state to
higher energy state
B) change of alignment of an electron in a magnetic field
C) change of alignment of a proton in a magnetic field
D) loss of an electron
E) molecular vibration - answer D) loss of an electron


Which of the following statements is true about a
molecular ion?
A) It is a compound that lost a pair of electrons.
B) It is a compound that gained a pair of electrons.

, C) It is a compound that gained one electron.
D) It is a compound that lost one electron.
E) It is a compound that carries a free radical and a
negative charge. - answer D) It is a compound that lost
one electron.


Which of the following statements best describes the
meaning of the following species:
[CH3CH2CH3] · + ?
A) It is the molecular ion of propane.
B) It is the parent ion of propane.
C) It is the radical cation of p
D) The m/z value is 44.
E) all of the above - answer E all of the above


Which of the following m/z values is the molecular ion for
2-butanone?
A) 15
B) 29
C) 43
D) 57
E) 72 - answer E) 72


What does m/z stand for and what does it mean? - answer
The m stands for the mass and z for the charge. Since
most fragments have a charge of
+1, m/z is the molecular weight of the fragment.