Which of the sulphides of group II is black or brownish black?

Options

A. PbS
B. HgS
C. `Bi_(2)S_(3)`
D. `CdS or As_(2)S_(3)`

Answer

To determine which of the sulfides of Group II is black or brownish-black, we can analyze the given options one by one:

1. **Lead Sulfide (PbS)**:
- Lead sulfide is known to form a black precipitate.
- Therefore, PbS is a candidate for the answer.

2. **Mercury Sulfide (HgS)**:
- Mercury sulfide also forms a black precipitate.
- Hence, HgS is another candidate for the answer.

3. **Bismuth Sulfide (Bi2S3)**:
- Bismuth sulfide is known to produce a dark black precipitate.
- Thus, Bi2S3 is also a candidate for the answer.

4. **Cadmium Sulfide (CdS)**:
- Cadmium sulfide forms a yellow precipitate, not black.
- Therefore, CdS is not a candidate for the answer.

5. **Arsenic Sulfide (As2S3)**:
- Arsenic sulfide also produces a yellow precipitate.
- Hence, As2S3 is not a candidate for the answer.

After analyzing all the options, we find that the sulfides that are black or brownish-black are:

- Lead Sulfide (PbS)
- Mercury Sulfide (HgS)
- Bismuth Sulfide (Bi2S3)

Thus, the correct answer to the question is that the sulfides of Group II that are black or brownish-black are PbS, HgS, and Bi2S3.

### Summary of the Answer:
The sulfides of Group II that are black or brownish-black are:
- PbS (Lead Sulfide)
- HgS (Mercury Sulfide)
- Bi2S3 (Bismuth Sulfide)