Final answer:
The vapor pressure of a liquid is the pressure of the gaseous molecules over the liquid at equilibrium. The boiling point of a liquid is the temperature at which its equilibrium vapor pressure is equal to the pressure exerted on the liquid by its gaseous surroundings.
Step-by-step explanation:
The vapor pressure of a liquid is the pressure of the gaseous molecules over the liquid at equilibrium. When the vapor pressure of the liquid is equal to the pressure of the gas above it, the liquid reaches its boiling point. The boiling point of a liquid is the temperature at which its equilibrium vapor pressure is equal to the pressure exerted on the liquid by its gaseous surroundings.