Question

Give the atomic number of the inert gas atom in which the total number of d-electrons is equal to the difference in the number of total p and s electrons.

Answer 1

The gas is $Kr$.
$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^6$
Total number of d-electrons=10
Total number of p-electrons=6+6+6=18
Total number of s-electrons=2+2+2+2=8
Difference in total number of p and s electrons=18-8=10
So inert gas is ${}_{36}Kr$.