`Which of the following complex or the complex ion will show geometrical isomerism?

Options

A. `[Pt(NH_(3))_(2)Cl^(2)]`
B. `[Pt(NH_(3))Cl_(5)]^(-)`
C. `[Pt(NH_(3))_(5)Cl]^(3+)`
D. `[Co(NH_(3))_(6)]Cl_(3)`

Explanation

To determine which complex or complex ion will show geometrical isomerism, we need to analyze the given complexes based on their structures and the arrangement of ligands around the central metal atom.

### Step-by-Step Solution:

1. **Understanding Geometrical Isomerism**:
- Geometrical isomerism occurs when ligands can be arranged in different spatial orientations around a central metal atom, leading to distinct isomers (cis and trans forms).
- For a complex to exhibit geometrical isomerism, it typically needs to have at least two different types of ligands and a coordination number that allows for different arrangements (like square planar or octahedral).

2. **Analyzing the First Complex**:
- The first complex is [Pt(NH₃)₂Cl₂].
- This complex has a coordination number of 4 and is likely to adopt a square planar geometry.
- In this arrangement, the two ammonia (NH₃) ligands can be on the same side (cis) or opposite sides (trans) of the chlorine (Cl) ligands.
- Therefore, this complex can show geometrical isomerism.

3. **Analyzing the Second Complex**:
- The second complex is [Pt(NH₃)Cl₅].
- Here, there are five chlorine ligands and one ammonia ligand.
- With five identical ligands (Cl), the ammonia can only occupy one position, and there is no possibility for cis or trans arrangements since all the chlorine ligands are identical.
- Thus, this complex does not exhibit geometrical isomerism.

4. **Analyzing the Third Complex**:
- The third complex is [Pt(NH₃)₅Cl].
- Similar to the previous case, there are five ammonia ligands and only one chlorine ligand.
- Again, the arrangement does not allow for cis or trans isomers due to the presence of multiple identical ligands.
- Therefore, this complex does not show geometrical isomerism.

5. **Analyzing the Fourth Complex**:
- The fourth complex is [Co(NH₃)₆].
- This complex has six identical ammonia ligands.
- Since all ligands are the same, there is no possibility for different spatial arrangements that would lead to cis or trans isomers.
- Thus, this complex does not exhibit geometrical isomerism.

### Conclusion:
Based on the analysis, the only complex that can show geometrical isomerism is the first one: **[Pt(NH₃)₂Cl₂]**.