The condition of free vapourisation throughout the liquid is called

Options

A. Freezing
B. Melting
C. Evaporation
D. Boiling

Answer

To answer the question, "The condition of free vaporization throughout the liquid is called," we need to analyze the concepts of vaporization, evaporation, and boiling.

### Step-by-Step Solution:

1. **Understanding Vaporization**:
- Vaporization is the process where a liquid turns into vapor. This can occur in two ways: evaporation and boiling.

2. **Defining Evaporation**:
- Evaporation is the process where molecules at the surface of a liquid gain enough energy to enter the gas phase. This can happen at any temperature and does not require the liquid to reach its boiling point.

3. **Defining Boiling**:
- Boiling occurs when the vapor pressure of the liquid equals the external pressure surrounding the liquid. At this point, vaporization occurs throughout the entire liquid, not just at the surface.

4. **Identifying Free Vaporization**:
- The term "free vaporization" refers to the condition where vaporization occurs throughout the entire volume of the liquid, which is characteristic of boiling.

5. **Conclusion**:
- Therefore, the condition of free vaporization throughout the liquid is called **boiling**.

### Final Answer:
The condition of free vaporization throughout the liquid is called **boiling**.