Specify the oxidation numbers of the metals in the following coordination entities:
(i) `[Co(H_(2)O)(CN)(en)_(2)]^(2+)`
(ii) `[CoBr_(2)(en)_(2)]^(+)`
(iii) `[PtCl_(4)]^(2-)`
(iv) `K_(3)[Fe(CN)_(6)]`
(v) `[Cr(NH_(3))_(3)Cl_(3)]`

Explanation

(i). `[overset(x)(C)o(overset(0)(H_2O)(Coverset(-1)(N))(eoverset(0)(n))_2]^(2+)`
`impliesx+(0)+(-1)+(0)=+2`
(ii). `[overset(x-1)(PtCl_4]^(2-)]`
`impliesx+(-1)xx4=-2,becausex=+2`
(iii). `[overset(x)(C)r(Noverset(0)(H)_3)_3(Coverset(-1)(l)_3)]`
`impliesx+(0)xx(3)+(-1)xx(3)=0,impliesx=+3`
(iv). `[(overset(x)(C)0overset(-1)(B)r_2)(eoverset(0)(n))_2]^(o+)`
`impliesx+(-1)xx(2)+(0)xx(2)=+1impliesx=+3`
(v). `overset(+1xx3)(K_3)[Fe(Coverset(-1)(N))_6]^(-3)`
`implies3(+1)xx x +(-1)(6)=0impliesx=+3`