An alkene molecule has a double bond whereas an alkyne molecule has a triple bond.
Properties of alkenes and alkynes are as follows.
Both are insoluble in water.
Their pH is less than 7.
Boiling point increases with increase in carbon atoms or chain length.
Their densities are less than the density of water.
Thus, we can conclude that out of the given options, their boiling points tend to increase with chain length is a property of both alkenes and alkynes.
