Question

as the pressure on a liquid is changed from 70 kpa to 80 kpa, the temperature at which the liquid will boil

Answer 1

Answer is: the boiling point will increase as the external pressure is increases.
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid, at that temperature the liquid changes into a vapor.
The boiling point of a liquid dependes upon the surrounding environmental pressure.