Which of the following reaction is employed to produce ozone in the laboratory ?

Options

A. Exposure of air to UV light
B. Reaction of `F_2` with `H_2O`
C. Reaction of `SO_2` with `H_2O_2`
D. Passage of silent electric discharge through oxygen

Answer

To determine which reaction is employed to produce ozone (O₃) in the laboratory, we need to analyze the given options based on the known methods of ozone production.

### Step-by-Step Solution:

1. **Understanding Ozone Production**: Ozone is typically produced by supplying energy to diatomic oxygen (O₂). This can be done through methods such as ultraviolet (UV) radiation or silent electric discharge.

2. **Evaluating Option 1**:
- **Exposure of air to UV light**: This method does produce ozone, but it is not a controlled laboratory method. It occurs naturally in the atmosphere, particularly in photochemical reactions. Therefore, this option is not correct for laboratory production.

3. **Evaluating Option 2**:
- **Reaction of F₂ with H₂O**: The reaction of fluorine gas (F₂) with water (H₂O) produces hydrofluoric acid (HF) and oxygen (O₂), but it does not produce ozone. Thus, this option is also incorrect.

4. **Evaluating Option 3**:
- **Reaction of sulfur dioxide (SO₂) with H₂O**: This reaction leads to the formation of sulfuric acid (H₂SO₄) and does not produce ozone. Therefore, this option is not correct.

5. **Evaluating Option 4**:
- **Passage of silent electric discharge through oxygen**: This method is a well-known laboratory technique for producing ozone. When an electric discharge is passed through oxygen, ozone is formed. This is the correct method for laboratory production of ozone.

### Conclusion:
The correct answer is **Option 4: Passage of silent electric discharge through oxygen**.