Which compound does not dissolve in hot dilute `HNO_(3)` ?

Options

A. `HgS`
B. `CuS`
C. `PbS`
D. `CdS`

Answer

To determine which compound does not dissolve in hot dilute HNO₃, we will analyze the behavior of each compound listed: HgS, CuS, PbS, and CdS.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- HgS (Mercury(II) sulfide)
- CuS (Copper(II) sulfide)
- PbS (Lead(II) sulfide)
- CdS (Cadmium sulfide)

2. **Reactions with Dilute HNO₃**:
- **HgS**: When HgS is treated with hot dilute HNO₃, it does not react to form a soluble nitrate. Therefore, it remains insoluble.
- **CuS**: When CuS reacts with hot dilute HNO₃, it forms copper nitrate (Cu(NO₃)₂), nitrogen monoxide (NO), sulfur (S), and water (H₂O). This indicates that CuS is soluble in hot dilute HNO₃.
- **PbS**: PbS also reacts with hot dilute HNO₃ to form lead nitrate (Pb(NO₃)₂), nitrogen monoxide (NO), and sulfur (S). Thus, PbS is soluble in hot dilute HNO₃.
- **CdS**: Similarly, CdS reacts with hot dilute HNO₃ to produce cadmium nitrate (Cd(NO₃)₂), nitrogen monoxide (NO), sulfur (S), and water (H₂O). Therefore, CdS is also soluble in hot dilute HNO₃.

3. **Conclusion**: Among the compounds analyzed, only HgS does not dissolve in hot dilute HNO₃. The other compounds (CuS, PbS, and CdS) all react and dissolve in the acid.

### Final Answer:
The compound that does not dissolve in hot dilute HNO₃ is **HgS**.

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