Explanation:
Boiling point - the temperature at which the the vapor pressure of the liquid equals the external atmospheric pressure.
From the question,
Butane and propane have different number of carbon atoms ,
Now to convert the liquid to gas , energy in the form of heat is provided , now to melt butane more amount of energy is required , due to more number of atoms present in butane , more energy is required and hence , butane has more boiling point .
In comparison to butane , propane has lesser atoms and hence , require less energy to convert liquid propane to gaseous propane , and therefore has less boiling point.
