Question

The mass number of an element is 41 and it has 21 neutrons in its nucleus. The electronic configuration of the element is:

• A. 2, 8, 8
• B. 2, 8, 8, 1
• C. 2, 8, 18, 13
• D. 2, 8, 8, 2

Answer 1

The correct option is D 2, 8, 8, 2

Here, it is given that:
Mass number of the element = 41
Total number of neutrons = 21
We know that mass number = number of protons + number of neutrons.
Therefore, number of protons = mass number - number of neutrons
= 41 - 21
= 20
There are 20 protons and 20 electrons.
K- shell, L-shell, M shell and N shell will have 2, 8, 8 and 2 electrons respectively.
So, the correct electronic configuration is (2, 8, 8, 2).