Which of the following sulphide(s) does/do not liberate `H_(2)S` on warming with dil. HCl?

Options

A. `HgS`
B. `ZnS`
C. `FeS`
D. `CuS`

Explanation

To determine which sulfides do not liberate hydrogen sulfide (H₂S) when warmed with dilute hydrochloric acid (HCl), we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the sulfides in the options**: The question provides several sulfides. We will check each one to see if it reacts with dilute HCl to produce H₂S.

2. **Check Option 1: HgS (Mercury(II) sulfide)**:
- When HgS is warmed with dilute HCl, there is no reaction. Therefore, HgS does not liberate H₂S.
- **Conclusion**: HgS does not evolve H₂S.

3. **Check Option 2: ZnS (Zinc sulfide)**:
- When ZnS is warmed with dilute HCl, it reacts to form ZnCl₂ and H₂S.
- **Reaction**: ZnS + 2HCl → ZnCl₂ + H₂S
- **Conclusion**: ZnS does liberate H₂S.

4. **Check Option 3: FeS (Iron(II) sulfide)**:
- When FeS is warmed with dilute HCl, it also reacts to produce FeCl₂ and H₂S.
- **Reaction**: FeS + 2HCl → FeCl₂ + H₂S
- **Conclusion**: FeS does liberate H₂S.

5. **Check Option 4: CuS (Copper(II) sulfide)**:
- When CuS is warmed with dilute HCl, there is no reaction. Therefore, CuS does not liberate H₂S.
- **Conclusion**: CuS does not evolve H₂S.

### Final Answer:
The sulfides that do not liberate H₂S on warming with dilute HCl are:
- **Option 1: HgS**
- **Option 4: CuS**