Which is a property of both alkenes and alkynes?

As the carbon chain gets longer, an alkene or alkyne molecule has more electrons and a larger surface area. This strengthens the attractions between molecules, so more energy is needed to boil them and their boiling points generally increase. These hydrocarbons are not highly water-soluble, and they are generally less dense than water; pH is not a useful measure for them.

AI-written and checked against the verified answer.