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

a) `K[Cr(H_(2)O_(2))_(2)(C_(2)O_(4))_(2)]`
The complex is octahedral in nature. It can exist as cis and trans isomers.

The cis isomer can also exist as pair of optical isomers.

b) `[Pt(NH_(3))(H_(2)O)Cl_(2)]`
the complex is square planar. It can exist as geometrical isomers i.e., cis and trans isomers.