Which of the following conversion is not brought about by ozone ? 

Options

A. `HF" to "F_(2)`
B. Moist KI to `I_(2)`
C. `Ag_(2)O" to "Ag`
D. `PbS" to "PbSO_(4)`

Answer

To determine which conversion is not brought about by ozone, we will analyze each option provided in the question. Ozone (O₃) is known for its strong oxidizing properties, and we will look at how it interacts with different substances.

### Step-by-Step Solution:

1. **Understanding Ozone as an Oxidizing Agent**:
- Ozone is a powerful oxidizing agent that can oxidize various substances. This means it can accept electrons from other substances, causing them to lose electrons and undergo oxidation.

2. **Analyzing Each Option**:
- **Option 1: HF to F₂**:
- In this reaction, ozone would need to oxidize fluoride ions (F⁻) to fluorine gas (F₂). However, fluoride ions are highly stable and do not easily undergo oxidation. Therefore, this reaction is not feasible.
- **Option 2: I⁻ to I₂**:
- Ozone can oxidize iodide ions (I⁻) to iodine (I₂). This reaction is possible and occurs readily.
- **Option 3: Ag₂O to Ag**:
- Ozone can also reduce silver oxide (Ag₂O) to metallic silver (Ag). This is another feasible reaction.
- **Option 4: PbS to PbSO₄**:
- Ozone can oxidize lead sulfide (PbS) to lead sulfate (PbSO₄). This reaction is also possible as it involves a significant oxidation of sulfur from -2 to +6.

3. **Conclusion**:
- After analyzing all the options, we conclude that the conversion that is not brought about by ozone is **Option 1: HF to F₂**. This is because the fluoride ion is too stable to be oxidized by ozone.

### Final Answer:
**Option 1: HF to F₂ is not brought about by ozone.**

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