Which electronic configuration is not observing the `(n + l)` rule.

Options

A. `1s^2, 2 s^2, 2p^6, 3 s^2, 3p^6, 3 d^1, 4 s^2`
B. `1 s^2, 2 s^2 2p^6, 3 s^2 3 p^6 3 d^7, 4 s^2`
C. `1 s^2, 2 s^2 2 p^6, 3 s^2 3p^6 3 d^5, 4 s^1`
D. `1 s, 2 s^2 2 p^6, 3 s^2 3p^6 3 d^8, 4 s^2`

Answer

C

Explanation

( c) `3d` subshell filled with `5` electrons (half-filled) is more stable than that filled with `4` electrons. `1, 4 s` electrons jump into `3d` subshell for more stability.