Question

Which has a higher boiling point: ether, aldehyde, alkane, or alcohol?

Answer 1

Alcohol, due to strongest intermolecular forces of attraction between molecules. (assuming similar lengths of carbon chains in each compound).

Explanation:

Assuming similar lengths of carbon chains of each, alcohol will have the highest boiling point due to presence of strong hydrogen bonds as intermolecular forces holding particles together.
However, as the carbon chain length increases, the molecules all get bigger, so this can also effect the strength of the intermolecular forces and hence the relative boiling points.