Answer

(i) Both geometrical (cis-, trans-) isomers for $\mathrm{K}[\mathrm{Cr}\mathrm{(H_2O)_2}\mathrm{(C_2O_4)_2}]$ can exist. Also, optical isomers for cis-isomer exist.

Geometrical isomers

Trans-isomer is optically inactive. On the other hand, cis-isomer is optically active.

(ii) Two optical isomers for $[\mathrm{CO(en)_3}]\mathrm{Cl_3}$

Two optical isomers are possible for this structure.

Other than this it can show Ionisation isomerism

(iii) $[\mathrm{Co}\mathrm{(NH_3)_5}\mathrm{(NO_2)}]\mathrm{(NO_3)_2}$

It can show linkage isomerism.

It can also show ionization isomerism.

(iv) Geometrical (cis-, trans-) isomers of $\left[\mathrm{Pt}\left(\mathrm{NH_3}\right)\left(\mathrm{H_2} \mathrm{O}\right) \mathrm{Cl_2}\right]$ can exist.

$\quad \quad $ Cis $\quad \quad \quad$ $\quad \quad \quad \quad$ $\quad \quad \quad$ Trans

Answer

When ionization isomers are dissolved in water, they ionize to give different ions. These ions then react differently with different reagents to give different products.

$ \left[\mathrm{Co}\left(\mathrm{NH_3}\right)_{5} \mathrm{Cl}\right] \mathrm{SO_4}+\mathrm{Ba}^{2+} \longrightarrow \underset{\text{White precipitate}}{\mathrm{BaSO_4} \downarrow} $

$\left[\mathrm{Co}\left(\mathrm{NH_3}\right)_{5} \mathrm{Cl}\right] \mathrm{SO_4}+\mathrm{Ag}^{+} \longrightarrow$ No reaction

$ {\left[\mathrm{Co}\left(\mathrm{NH_3}\right)_{5} \mathrm{SO_4}\right] \mathrm{Cl}+\mathrm{Ba}^{2+} \longrightarrow \text { No reaction }} $

$ [\mathrm{Co}(\mathrm{NH_3})_{5} \mathrm{SO_4}] \mathrm{Cl}+\mathrm{Ag}^{+} \longrightarrow \underset{\text{White precipitate }}{\mathrm{AgCl} \downarrow} $