The number of d-electron retained in `Fe^(2) ("At no. of" Fe =26)` ion is.

Options

A. `3`
B. `4`
C. `5`
D. `6`

Answer

4

Explanation

`_(26)Fe=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(6), 4s^(2)`,
`Fe^(++)=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(6)`
The number of d-electrons retained in `Fe^(2+)=6`
Therefore, (4) is correct option.