10 Mass spectrometers are used in chemical analysis. (a) In which region of this mass spectrometer are the ions accelerated?
(1)
A region P
B region Q
C region R
D region S
ANSWER
Region Q
Analysis of Option/Explanation
The diagram mentioned in the question may be compared with the mentioned below diagram for understanding.
Hence, region Q is the region where ions are accelerated. Therefore, correct answer is option B.
(b) Four iron ions are present in a stream of ions in a mass spectrometer.
The paths of these ions are shown.
Which of these ions will follow path 1 through the mass spectrometer?
(1)
A 54Fe+
B 54Fe2+
C 56Fe+
D 56Fe2+
ANSWER
B 54Fe2+
Analysis of Option/Explanation
It is necessary to look on the figure provided in the question, when student sees path 1 , it is observed that path 1 deflects the most as compared to other parths. Also, it is well known that “lighter ions are deflected the most than heavier ions”. i.e. student need to know the “m/e” ratio.
Option A
Option B
Option C
Option D
The lowest value of m/e is for Option B (54Fe2+), hence it will deflect the most and follow path 1.
(c) Naturally‑occurring chlorine has two isotopes, 35Cl and 37Cl.
How many peaks due to the singly-charged molecular ions are seen in the mass spectrum of chlorine, Cl2?
(1)
A 1
B 2
C 3
D 4
ANSWER
C 3
Analysis of Option/Explanation
Let’s see how much number of peaks can be form?
35Cl35Cl+
37Cl37Cl+
35Cl37Cl+
Hence, total number of three (03) peaks will be formed. Therefore, option C is correct.
