Question -
Answer -
(i) [Co(H2O)(CN)(en)2]2+ (ii) [CoBr2(en)2]+ (iii) [PtCl4]2−
(iv) K3[Fe(CN)6] (v) [Cr(NH3)3Cl3]
Answer
(i) 
Letthe oxidation number of Co be x.
The charge on the complex is +2.
(ii)
Letthe oxidation number of Pt be x.
The charge on the complex is −2.
x + 4(−1) = −2
x = + 2
(iv) 
