Amongst the following ions which one has the highest magnetic moment value?
(i). `[Cr(H_2O)_6]^(3+)`
(ii). `[Fe(H_2O)_6]^(2+)`
(iii). `[Zn(H_2O)]^(2+)`

Explanation

The oxidation states are Cr (III) Fe (II) and Zn(II)
Electronic configuration of `Cr^(3+)=3d^(3)` unpaired electron=3
Electronic configuration of `Fe^(2+)=3d^(6)` unpaired electron =4
Electronic configuration of `Zn^(2+)=3d^(10)` unpaired electrons =0
`mu=sqrt(n(n+2))`
where V is number of unpaired electrons Hence (ii) has highest value of magnetic moment.