Which compound has the highest boiling point?

The compound with the highest boiling point among the choices is alcohol. This is primarily due to the presence of a hydroxyl (-OH) functional group in alcohols, which allows them to form hydrogen bonds with each other. Hydrogen bonding is a strong type of intermolecular force that requires a significant amount of energy to overcome, resulting in higher boiling points compared to compounds that do not participate in such strong interactions.

Alkanes, while they may have varying boiling points depending on their molecular weight, primarily exhibit dispersion forces (also known as London forces), which are generally weaker than hydrogen bonds. Aldehydes and ethers also engage in dipole-dipole interactions and dispersion forces but are unable to form hydrogen bonds in the same way that alcohols can. Thus, the presence of hydrogen bonding in alcohols leads to their comparatively elevated boiling point, making them the compound with the highest boiling point in this context.