Which of the following coordination compounds exhibits geometrical isomerism?

Solution

1. The complex ${\text{[Pt(NH}}_3{)}_2{\text{Cl}}_2]$ is a square planar complex of the type ${\text{MA}}_2{\text{B}}_2$.
2. Square planar complexes with the general formula ${\text{MA}}_2{\text{B}}_2$ can exist as cis and trans isomers.
3. The other complexes ${\text{[Zn(NH}}_3{)}_4{]}^{2+}$, ${\text{[Ni(CO)}}_4]$, and ${\text{[Cu(NH}}_3{)}_4{]}^{2+}$ are tetrahedral and do not show geometrical isomerism.
4. Hence the answer is (A).