If cold water is poured on flask containing very hot distilled water and water vapour, the water inside the flask started to boil below `100^(@)`C. The principle involved is __________.

Explanation

To solve the question regarding the phenomenon observed when cold water is poured on a flask containing very hot distilled water and water vapor, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Boiling Point**: The boiling point of a liquid is the temperature at which its vapor pressure equals the external pressure surrounding the liquid. Under normal atmospheric pressure, water boils at 100°C.

2. **Effect of Temperature on Vapor Pressure**: When the temperature of the water increases, its vapor pressure also increases. In the case of very hot distilled water, the vapor pressure is significantly higher than that of cold water.

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