Which of the following white ppts are insoluble in `NH_(3)`?

Options

A. `AgCl`
B. `Hg_(2)Cl_(2)`
C. `PbCl_(2)`
D. All of these

Answer

To determine which of the given white precipitates are insoluble in ammonia (NH₃), we will analyze each compound step by step.

### Step 1: Analyze AgCl (Silver Chloride)
- **Observation**: AgCl is a white precipitate.
- **Reaction with NH₃**: When AgCl reacts with ammonia, it forms a soluble complex:
\[ \text{AgCl} + 2 \text{NH}_3 \rightarrow \text{[Ag(NH}_3\text{)}_2]^+ + \text{Cl}^- \]
- **Conclusion**: AgCl is soluble in ammonia.

### Step 2: Analyze Hg₂Cl₂ (Mercurous Chloride)
- **Observation**: Hg₂Cl₂ is also a white precipitate.
- **Reaction with NH₃**: When Hg₂Cl₂ reacts with ammonia, it forms:
\[ \text{Hg}_2\text{Cl}_2 + 2 \text{NH}_3 \rightarrow \text{Hg} + \text{Hg(NH}_2\text{Cl)} + \text{NH}_4\text{Cl} \]
- **Conclusion**: The white precipitate of Hg₂Cl₂ is also soluble in ammonia due to the formation of the complex Hg(NH₂Cl).

### Step 3: Analyze PbCl₂ (Lead Chloride)
- **Observation**: PbCl₂ is a white precipitate.
- **Solubility in NH₃**: PbCl₂ is known to be insoluble in ammonia. It is only soluble in hot water.
- **Conclusion**: PbCl₂ remains insoluble in ammonia.

### Final Conclusion
- **Answer**: The only white precipitate that is insoluble in ammonia is **PbCl₂** (Option C).

### Summary of Options
- **Option A (AgCl)**: Soluble in NH₃.
- **Option B (Hg₂Cl₂)**: Soluble in NH₃.
- **Option C (PbCl₂)**: Insoluble in NH₃.
- **Option D (All of these)**: Incorrect.

Thus, the correct answer is **Option C: PbCl₂**.

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