Amongst the following, the lowest degree of paramgnetism per mole of the compound at `298 K` will be shown by

Options

A. `MnSO_4 . 4H_2O`
B. `CuSO_4 . 5H_2O`
C. `FeSO_4 . 6H_2O`
D. `NiSO_4 . 6H_2O`

Answer

B

Explanation

`Mn^(2+)` in `MnSO_4 . 4H_2O - d^5` configuration 5 unpaired `e^-`
`Cu^(2+)` in `CuSO_4. 5H_2O - d^9` configuration 1 unpaired `e^-`
`Fe^(2+)` in `FeSO_4 . 6H_2O - d^6` configuration 4 unpaired `e^-`
`Ni^(2+)` in `NiSO_4 . 6H_2O - d^8` configuration 2 unpaired `e^-`
`therefore CuSO_4 . 5H_2O` - lowest degree of paramagnetism