Answer
London Dispersion Forces
Work Step by Step
As you will learn later, boiling point increases with an increase in intermolecular forces. Since there is no hydrogen bonding between hydrocarbons, we see that the London Dispersion Force is the main factor that contributes to the boiling point. As molecules get larger, they are able to polarize more, leading to greater intermolecular attractions. Because of these stronger attractions, more energy is needed to break them. This leads to a higher boiling point.