Amongst the following ions, which one has the highest magnetic moment
`[Cr(H_(2)O)_(6)]^(3+)`
`[Fe(H_(2)O)_(6)]^(2+)`
(iii) `[Zn(H_(2)O)_(6)]^(2+)`

Explanation

The oxidation state are: Cr(lll), Fe (II)and `Zn (II)`
`E.C. of Cr^(3+) = 3d^(3)`, unpaired electrons =3 (inner orbital complex)
`E. C. of Fe^(2+) = 3d^(6)`unpaired electrons = 4 (outer orbital:/high spin complex)
` E.C. of Zn^(2+) = 3d^(10)`, unpaired electrons = 0 (outer orbital complex)
`mu= sqrt(n(n+2))` Hence (ii) has highest magnetic moment.