Which one of the following ions has electronic configuration `[Ar]3d^(6)` ? `(At. Nos. Mn = 25, Fe = 26, Co = 27, Ni = 28)`

Options

A. `Co^(3+)`
B. `Ni^(3+)`
C. `Mn^(3+)`
D. `Fe^(3+)`

Answer

A

Explanation

`Co (Z = 27) : 3d^(7) 4s^(2) , Co^(3+) (Z = 27) : 3d^(6)`
`Ni (Z = 28) : 3d^(8) 4s^(2) , Ni^(3+) (Z = 27) : 3d^(7)`
`Mn (Z = 25) : 3d^(5) 4s^(2) , Mn^(3+) (Z = 27) : 3d^(4)`
`Fe (Z = 26) : 3d^(6) 4s^(2) , Fe^(3+) (Z = 26) : 3d^(5)`