The pair having the same magnetic moment is
[at. No. `Cr = 24, Mn = 25, Fe = 26 " and " Co = 27]`

Options

A. `[Cr(H_(2)O)_(6)]^(2+)` and `[CoCl_(4)]^(2-)`
B. `[Cr(H_(2)O)_(6)]^(2+) and [Fe(H_(2)O)_(6)]^(2+)`
C. `[Mn(H_(2)O)_(6)]^(2+) and [Cr(H_(2)O)_(6)]^(2+)`
D. `[CoCl_(4)]^(2-) and [Fe(H_(2)O)_(6)]^(2+)`

Answer

B

Explanation

`[Ci(H_(2)O)_(6)]^(2+):Cr^(2+)=[Ar]3d^(4)4s^(0)`

Thus, `[Cr(H_(2)O)_(6)]^(2+)` and `[Fe(H_(2)O)_(6)]^(2+)` have the same number of unpaired electrons and hence have same magnetic moment.