Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Only weak London dispersion forces hold molecules of nonpolar alkanes together in the liquid phase. Consequently, less energy is required to break these molecules away from the surface of the liquid and turn them into a vapor. The stronger hydrogen bonding between alcohol molecules means that more energy is required to convert the liquid to vapor, and boiling points are therefore high. Answer: stronger hydrogen bonding
Output:
What kind of bonding between alcohol molecules means that more energy is required to convert the liquid to vapor, and boiling points are therefore high?