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

(i). `K[Cr(H_2O)_2(C_2O_4)_2]` is of `[M(AA)_2b_2]^(n+-)` type it shows both geometrical isomers (cis and trans)
(ii). `[Co(en)_3Cl_3` is of `[M(AA)_3]^(n+-)` type it shows optical isomers (d- and l-) of cis.
(iii). There are 2 ionisation and 2 linkage isomers. Compounds of `[Ma_5b]^(n+-)` type neither shows geometrical nor optical isomers. Ionisation isomers:
`[Co(NH_3)_5(NO_2)](NO_3)_2`
`[Co(NH_3)_5(NO_3)](NO_3)(NO_2)`
Linkage isomers:
`[Co(NH_3)_5(NO_2)](NO_3)_2,[Co(NH_3)_5(ONO)](NO_3)_2`
(iv). `Pt[(NH_3)(H_2O)Cl_2]` is of `[Ma_2Bc]^(n+-)` type It shows geometrical isomers (cis and trans)