What effect does a decreasing the pressure or b increasing t

What effect does (a) decreasing the pressure or (b) increasing the pressure above a liquid have on the liquids boiling point?

Solution

Boiling point of a liquid is the temperature at which the vapour pressure of the liquid is equal to the external pressure.

So when pressure above a liquid is decreased, the vapour pressure needed to induce boiling is also decreased

Hence boiling point of the liquid decreases .

Similarly if the pressure above a liquid is increased, vapour pressure needed increases and boiling point increases.