The correct order of the number of unpaired electrons in the ions `Cu^(2+), Ni^(2+), Fe^(3+)`, and `Cr^(3+)`is

Options

A. `Cu^(2+) gt Ni^(2+) gt Cr^(3+) gt Fe^(3+)`
B. `Cr^(3+) gt Fe^(2+) gt Ni^(2+) gt Ce^(2+)`
C. `Fe^(3+) gt Cr^(3+) gt Cu^(2+) gt Ni^(2+)`
D. `Fe^(3+) gt Cr^(3+) gt Ni^(2+) gt Cu^(2+)`

Answer

D

Explanation

`Cu^(2+) : 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 3d^(9)` (One unpaired electron)
`Ni^^(2+) : 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 3d^(8)` (Two unpaired electrons)
`Fe^(3+) : 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 3d^(5)` (Five unpaired electrons)
`Cr^(3+) : 1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 3d^(3)`
(Three unpaired electrons)
`:.` Correct order of unpaired electrons : `Fe^(3+) gt Cr^(3+) gt Ni^(2+) gt Cu^(2+)`