The boiling point of a pure substance is defined as the temperature at which:

Athe kinetic energy of the molecules begins to increase
Bthe vapor pressure equals the external pressure
Cthe molecules of the substance break apart
Dthe liquid phase can be completely evaporated

thanks in advance

Verified Answer :

C, because as the temperature increases the molecules get farther apart and  at one point turn into a gas!

Answer: B) the vapor pressure equals the external pressure.


Explanation: Boiling point is the temperature at which pressure exerted by the vapors on the liquid is equal to the atmospheric pressure surrounding the liquid.


The kinetic energy begins to increase when the liquid is heated.


The molecules move farther from each other when liquid changes to vapor form.


The liquid phase can be completely evaporated if we continue to boil.