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 the behavior of each sulfide listed: HgS (mercury sulfide), ZnS (zinc sulfide), FeS (iron sulfide), and CuS (copper sulfide).

### Step-by-Step Solution:

1. **Identify the sulfides and their colors**:
- HgS (mercury sulfide) - black
- ZnS (zinc sulfide) - white
- FeS (iron sulfide) - black
- CuS (copper sulfide) - black

2. **Understand the general behavior of sulfides with dilute HCl**:
- Black sulfides typically do not liberate H₂S when warmed with non-oxidizing acids like dilute HCl, with the exception of iron sulfide (FeS).
- White sulfides, like zinc sulfide, generally do not liberate H₂S.

3. **Analyze each sulfide**:
- **HgS**: As a black sulfide, it does not liberate H₂S when warmed with dilute HCl.
- **ZnS**: Being a white sulfide, it does not liberate H₂S when warmed with dilute HCl.
- **FeS**: Although it is black, it does liberate H₂S when warmed with dilute HCl.
- **CuS**: As a black sulfide, it does not liberate H₂S when warmed with dilute HCl.

4. **Conclusion**:
- The sulfides that do not liberate H₂S on warming with dilute HCl are HgS (mercury sulfide), ZnS (zinc sulfide), and CuS (copper sulfide).

### Final Answer:
The sulfides that do not liberate H₂S on warming with dilute HCl are **HgS and CuS**.