Which of the following complex compounds exhibits cis-trans isomerism
(a) `[PtCI_(2)(NH_(3))_(2)]`
(b) `[PdCI_(2)BrI]`
(c ) `[Pt(NH_(3))(py)(CI)(Br)]`
All ofh these .

Explanation

To determine which of the given complex compounds exhibit cis-trans isomerism, we need to analyze each compound based on their coordination geometry and the arrangement of ligands around the central metal atom. Let's go through each option step by step.

### Step 1: Analyze the first compound `[PtCl2(NH3)2]`

1. **Identify the coordination number and geometry**:
- The central metal is platinum (Pt) with a coordination number of 4 (two Cl and two NH3).
- The geometry is square planar.

2. **Determine possible isomers**:
- In a square planar geometry with two pairs of identical ligands, we can have cis and trans isomers.
- **Cis form**: Both NH3 ligands are adjacent to each other.
- **Trans form**: The NH3 ligands are opposite each other.

**Conclusion**: This compound exhibits cis-trans isomerism.

### Step 2: Analyze the second compound `[PdCl2BrI]`

1. **Identify the coordination number and geometry**:
- The central metal is palladium (Pd) with a coordination number of 4 (two Cl, one Br, and one I).
- The geometry is square planar.

2. **Determine possible isomers**:
- In a square planar geometry with two identical ligands (Cl), we can have cis and trans isomers.
- **Cis form**: The two Cl ligands are adjacent.
- **Trans form**: The two Cl ligands are opposite each other.

**Conclusion**: This compound also exhibits cis-trans isomerism.

### Step 3: Analyze the third compound `[Pt(NH3)(py)(Cl)(Br)]`

1. **Identify the coordination number and geometry**:
- The central metal is platinum (Pt) with a coordination number of 4 (one NH3, one pyridine (py), one Cl, and one Br).
- The geometry is square planar.

2. **Determine possible isomers**:
- In this case, all four ligands are different, but we can still have cis and trans arrangements.
- **Cis form**: NH3 and py are adjacent, while Cl and Br are adjacent.
- **Trans form**: NH3 and py are opposite each other, while Cl and Br are opposite.

**Conclusion**: This compound also exhibits cis-trans isomerism.

### Final Conclusion

Since all three compounds exhibit cis-trans isomerism, the answer to the question is:
**All of these.**

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