If the electronic configuration of an element is 1s22s22p63s23p63d24s2, the four electrons that participate in the chemical bond formation will be from :

1. 3p6 2. 3p6, 4s2
3. 3p6, 3d2 4. 3d2, 4s2

HINT: Electrons of ns and (n-1)d subshell take part in bond formation.

Explanation:

STEP 1: 

The given electronic configuration shows that an element is a vanadium (Z = 22). It belongs to the d-block of the periodic table. In transition elements i.e., d-block elements, electrons of ns and (n-1)d subshell take part in bond formation.

STEP  2: 

Hence, 3d and 4s electrons participate in bond formation. Therefore, option 4 is the correct answer.