Arrange `S, P` and `As` in order of increasing ionisation energy.

Options

A. `S lt P lt As`
B. `P lt S lt As`
C. `As lt S lt P`
D. `As lt P lt S`

Answer

C

Explanation

`IE_(1)` of `P gt S` due to half - filled stable configuration `(3s^(2) , 3p^(3))` of `P`. Moreover, `P` and `As` both belong to group `15`, but `P` is in the `3rd` period and `As` is in the `4th` period and `IE_(1)` decreases down the group `(darr )`. Hence, the answer is (c).