Jack was getting late for the school, so, his mother advised him to pour hot milk from a glass into a saucer and then drink. Why did she say so? Give reason.

Explanation

Rate of evaporation depends on surface area of liquids. The more is the surface area of the liquid, the more is the rate of evaporation of the liquid. This is due to increased number of suface molecules.
When these surface molecules are exposed to atmosphere, they gain energy and escape into atmosphese. And hence hot milk in the saucer gets cooled.