The example of homogeneous catalysis is

Options

A. Formation of `NH_(3)` in Haber's process
B. Formation of NO in Ostwald's process
C. Formation of `SO_(3)` in Lead chamber process
D. Formation of `SO_(3)` in Contact process

Answer

To determine the example of homogeneous catalysis from the given options, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand Homogeneous Catalysis**:
- Homogeneous catalysis occurs when the reactants and the catalyst are in the same phase (either all gases, all liquids, or all solids).
- In contrast, heterogeneous catalysis occurs when the reactants and the catalyst are in different phases.

2. **Analyze Each Option**:
- **Option 1: Formation of Ammonia in Haber’s Process**:
- Reactants: Nitrogen (gas) and Hydrogen (gas)
- Catalyst: Finely divided Iron (solid)
- Since the catalyst is in a different phase (solid), this is an example of heterogeneous catalysis.

- **Option 2: Formation of NO in Ostwald’s Process**:
- Reactants: Ammonia (gas) and Oxygen (gas)
- Catalyst: Platinum gauze (solid)
- Again, the catalyst is in a different phase (solid), making this an example of heterogeneous catalysis.

- **Option 3: Formation of Sulfur Trioxide in Lead Chamber Process**:
- Reactants: Sulfur Dioxide (gas) and Oxygen (gas)
- Catalyst: Oxides of Nitrogen (gas)
- Here, both the reactants and the catalyst are in the same phase (gaseous), indicating that this is an example of homogeneous catalysis.

- **Option 4: Formation of SO3 in Contact Process**:
- Reactants: Sulfur Dioxide (gas) and Oxygen (gas)
- Catalyst: Platinum (solid)
- The catalyst is in a different phase (solid), so this is also an example of heterogeneous catalysis.

3. **Identify the Correct Option**:
- From the analysis, **Option 3 (Formation of Sulfur Trioxide in Lead Chamber Process)** is the only example of homogeneous catalysis since both the reactants and the catalyst are in the gaseous phase.

### Final Answer:
The example of homogeneous catalysis is **Option 3: Formation of Sulfur Trioxide in Lead Chamber Process**.