Question

A neutral atom of an element has 2K, 8L, 9M and 2N electrons. The total number of $s$ electrons are:

• A. 8
• B. 6
• C. 4
• D. 10

Answer 1

Answer: (A)

8

A neutral atom of an element has 2K, 8L, 9M and 2N electrons so it has total electrons of 21.

So it has 21 protons and its atomic no is 21.

And electronic configuration of element is:

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{1}4s^2$

So, the number of s electrons are 8.

Hence, the correct option is $A$