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

(i) `[Cr(C_(2)O_(4))_(3)]^(3) rArr [Cr("ox")_(3)]^(3-)`

(ii) (cis - isomer only) Cis - `[PtCl_(2)(en)_(2)]^(2+)`
(iii) (cis-isomer only) Cis - `[Cr(NH_(3))_(2)Cl_(2)(en)]^(+)`