Which of the following compounds exhibit geometrical isomer ?

Options

A. `Pt(NH_(3))_(2)Cl_(2)`
B. `Zn(NH_(3))_(2)Cl_(2)`
C. `Pt(NH_(3))_(3)Cl`
D. All of these

Answer

To determine which of the given compounds exhibit geometrical isomerism, we need to analyze each compound based on the criteria for geometrical isomerism, particularly focusing on the presence of at least two identical atoms and the molecular geometry of the compound.

### Step-by-Step Solution:

1. **Understanding Geometrical Isomerism**:
- Geometrical isomers have the same molecular formula but different spatial arrangements of atoms.
- This is often referred to as cis-trans isomerism. In cis isomers, similar atoms are positioned at 90 degrees to each other, while in trans isomers, they are positioned at 180 degrees.

2. **Analyzing Option A: Pt(NH3)Cl2**:
- This compound has a square planar geometry.
- In a square planar arrangement, we can have two types of geometrical isomers:
- **Cis Isomer**: Both Cl atoms are adjacent (90 degrees).
- **Trans Isomer**: Both Cl atoms are opposite each other (180 degrees).
- Therefore, Pt(NH3)Cl2 can exhibit both cis and trans isomerism.

3. **Analyzing Option B: [Co(NH3)4Cl2]+**:
- This compound has an octahedral geometry.
- Similar to the previous case, it can also exhibit geometrical isomerism:
- **Cis Isomer**: Two Cl atoms adjacent to each other.
- **Trans Isomer**: Two Cl atoms opposite each other.
- Thus, [Co(NH3)4Cl2]+ can also exhibit geometrical isomerism.

4. **Analyzing Option C: Zn(NH3)2Cl2**:
- This compound has a tetrahedral geometry.
- In tetrahedral complexes, the angles between the bonds are approximately 109.5 degrees.
- Since there are no 90-degree or 180-degree arrangements possible, Zn(NH3)2Cl2 does not exhibit geometrical isomerism.

5. **Conclusion**:
- From the analysis, we conclude that:
- **Option A (Pt(NH3)Cl2)** and **Option B ([Co(NH3)4Cl2]+)** can exhibit geometrical isomerism.
- **Option C (Zn(NH3)2Cl2)** does not exhibit geometrical isomerism.

### Final Answer:
The compounds that exhibit geometrical isomerism are **Option A (Pt(NH3)Cl2)** and **Option B ([Co(NH3)4Cl2]+)**.