Which one of the following ions exhibits d - d transition and paramagnetism as well -

Options

A. `MnO_(4)^(2-)`
B. `CrO_(4)^(2-)`
C. `MnO_(4)^(-)`
D. `Cr_(2)O_(7)^(2-)`

Answer

A

Explanation

`MnO_(4)^(2-)rarr Mn^(6+):[Ar]3d^(1)`
Only `MnO_(4)^(2-)` has one d - electron. Thus it can undergo d - d transition.