Draw the structures of optical isomers of:
(i). `[Cr(C_2O_4)_3]^(3-)`
(ii). `[PtCl_2(en)_2]^(2+)`
(iii). `[Cr(NH_3)_2Cl_2(en)]^(o+)`

Explanation

`[CoCl_2(en)_2]^(o+)` is of `[M(AA)_2b_2]^(n+-)` type
(ii). `[Co(NH_3)Cl(en)_2]^(2+)` is of `[M(AA)_2ab]^(n+-)` type.
(iii). `[Co(NH_3)_2Cl_2(en)]^(o+)` is of `[M(AA)a_2b_2]^(n+-)` type.