The number of `d` electrons in `Fe^(2+)` (atomic number of `Fe = 26`) is not equal to that of the:

Options

A. `p`-electrons in `Ne` (At. No. = 10)
B. `s`-electrons in `Mg` (At. No = 12)
C. `d`-electrons in `Fe`
D. `p`-electron in `Cl^(-)` (At. No. of Cl =17).

Answer

D

Explanation

(d) `._26 Fe = [AR]3d^6, 4s^2`
`Fe^(2+) = [Ar] 3d^6, 4s ^(0)d^(6)`
Number of d-electrons `= 6`
`._17 Cl = [Ne]3s^2, 3 p^5`
`Cl^- = [Ne]3s^2 , 3p^6`
Number of p-electrons `= 6`.