The boiling point of a liquid at atmospheric pressure is the temperature:
a. at which bubbles of vapor expand within the liqud
b. at which the liquid solidifies
c. at which the vapor pressure first exceeds the critical temperature
d. at which the vapor pressure is equal to the atmospheric pressure
d. 100 degree C
Look up the definition of boiling point. That's all you need t know, the definition.
The boiling point of a liquid at atmospheric pressure is the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure.
To determine the boiling point, we need to know the vapor pressure of the liquid at different temperatures and compare it to the atmospheric pressure. When the vapor pressure of the liquid reaches the same value as the atmospheric pressure, the liquid is said to be boiling.
Option (d) is the correct answer because it states that the boiling point is the temperature at which the vapor pressure is equal to the atmospheric pressure.