Indicate the type of isomerism exhibited by the following complexes and draw the structures for these isomers:
(i) `K[Cr(H_(2)O)_(2)(C_(2)O_(4))_(2)`
(ii) `[Co(en)_(3)]Cl_(3)`
(iii) `[Co(NH_(3))_(5)(NO_(2))](NO_(3))_(2)`
(iv) `[Pt(NH_(3))(H_(2)O)Cl_(2)]`

Explanation

(ii) Both optical isomers exist
(iii) Ionization isomers : `[Co(NH_(3))_(5)(NO_(2))](NO_(3))_(2),[Co(NH_(3))_(5)(NO_(3))](NO_(2))(NO_(3))`
Linkage isomers : `[Co(NH_(3))_(5)(NO_(2))](NO_(3))_(2),[Co(NH_(3))_(5)(ONO)](NO_(3))_(2)`
(iv)

Octahedral complexes of the type `[MA_(5)B]` do not show geometrical and optical isomerism.