Question

If the electronic configuration of an element is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{2}4s^2,$ the four electrons involved in chemical bond formation will be ---------

• A. $3p^{6}3d^2$
• B. $3p^{6}4s^2$
• C. $3d^{2}4s^2$
• D. $3p^6$

Answer 1

The correct option is C $3d^{2}4s^2$

Valence shell electrons:

Outermost shell, having maximum $‘n^{\prime }$ value, is called the valence shell and the electrons present in it are called valence shell electrons.

It is the electronic configuration of a $d-$block element. In $d-$block elements, the electrons present in d-orbital of penultimate shell also participate in chemical reactions. So, the electrons from the s-orbital of $4^{th}$ shell (valence shell) and d-orbitals of $3^{rd}$ shell (penultimate shell) participate in bond formation.

Thus, the $4$ electrons involved in chemical bond formation will be $3d^{2}4s^2,$ i.e., correct answer is option $\left(D\right).$