Boiling point is the temperature at which the vapour pressure becomes equal to..........

Explanation

**Step-by-Step Solution:**

1. **Understanding Boiling Point**: The boiling point of a liquid is defined as the temperature at which the liquid's vapor pressure equals the pressure surrounding the liquid.

2. **Identifying the Relevant Pressure**: The surrounding pressure can vary, but in most cases, it refers to the atmospheric pressure when we are discussing boiling points at standard conditions.

3. **Equating Pressures**: At the boiling point, the vapor pressure of the liquid becomes equal to the external pressure (which is often the atmospheric pressure).

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