Which of the following configuration is correct for iron ?

Options

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

Answer

D

Explanation

`Fe(Z=26) : 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 4s^(2) 3d^(6)`