Conversion of a substance directly from solid to vapour state is known as

Options

A. distillation
B. evaporation
C. vapourisation
D. sublimation

Answer

To answer the question about the conversion of a substance directly from solid to vapor state, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Terms**:
- First, we need to clarify what is meant by "conversion of a substance" and the states of matter involved: solid, liquid, and gas (vapor).

2. **Identifying the Process**:
- The question specifically asks for the process where a solid changes directly into a gas without passing through the liquid state.

3. **Defining the Process**:
- The process where a solid turns directly into a gas is known as sublimation.

4. **Examples of Sublimation**:
- Common examples of substances that undergo sublimation include ammonium chloride and camphor. These substances can change from solid to gas without becoming liquid.

5. **Conclusion**:
- Therefore, the conversion of a substance directly from solid to vapor state is called sublimation.

### Final Answer:
The conversion of a substance directly from solid to vapor state is known as **sublimation**.

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