Which of the following compounds exhibit geometrical isomer?

[Pt(NH₃)₂Cl₂]

The correct answer is option 1. [Pt(NH₃)₂Cl₂].

Geometrical isomerism occurs in coordination compounds when there is restricted rotation around a coordination bond, leading to the formation of different spatial arrangements of ligands around the central metal atom.

Let us analyze each compound:

1. \([Pt(NH_3)_2Cl_2]\): This complex has two different ligands, ammonia (\(NH_3\)) and chloride (\(Cl\)), which can be arranged in cis or trans configurations. Therefore, it exhibits geometrical isomerism.

2. \([Zn(NH_3)_2Cl_2]\): Zinc typically forms tetrahedral complexes with ammonia and chloride ligands. However, in tetrahedral complexes, there is free rotation around the coordination bonds, so geometrical isomerism does not occur.

3. \([Pt(NH_3)_3Cl]\): This complex has three same type of ligand, ammonia (\(NH_3\)), so geometrical isomers are not possible.

Therefore, only the compound \([Pt(NH_3)_2Cl_2]\) exhibits geometrical isomerism.

The correct answer is \([Pt(NH_3)_2Cl_2]\).