Which of the substance is purified by sublimation

Options

A. Benzoic acid
B. Camphor
C. Naphthalene
D. All of these

Explanation

To determine which substances can be purified by sublimation, we need to understand the process of sublimation and the properties of the given compounds: benzoic acid, camphor, and naphthalene.

### Step-by-Step Solution:

1. **Understanding Sublimation**:
- Sublimation is the process where a solid changes directly into a gas without passing through the liquid state. This process can also occur in reverse, where a gas changes directly into a solid.

2. **Identifying Sublimable Substances**:
- We need to analyze the three given substances: benzoic acid, camphor, and naphthalene, to see if they can undergo sublimation.

3. **Benzoic Acid**:
- Benzoic acid can sublime when heated. It transitions from a solid to a gas without becoming liquid. Therefore, it is sublimable.

4. **Camphor**:
- Camphor is well-known for its ability to sublime. When heated, it changes directly from solid to gas. Thus, camphor is also sublimable.

5. **Naphthalene**:
- Naphthalene is another compound that can sublime. It can change from solid to gas upon heating, making it sublimable as well.

6. **Conclusion**:
- All three substances—benzoic acid, camphor, and naphthalene—can be purified by sublimation. If mixed with non-sublimable impurities, the sublimable substances will transition to gas and can be collected separately.

### Final Answer:
All of the substances (benzoic acid, camphor, and naphthalene) can be purified by sublimation.