Question

The inert gas atom in which the total number of d-electrons is equal to the difference in number of total p and s-electrons, is:

• A. He
• B. Ne
• C. Ar
• D. Kr

Answer 1

The correct option is D Kr

He, Ne and Ar do not have any d-electrons, while the difference of their s and p electrons in not zero.

The electronic configuration of krypton (atomic number is 36) is
$1s^2,2s^2,2p^6,3s^2,3p^6,3d^{10},4s^2,4p^6$.
Total $s$-electrons are 8 and total $p$-electrons are 18.
Thus the difference is 10 and total d-electrons are 10 which are equal to 0. Hence, option (d) is the correct answer.