* Alkanes are hydrocarbons with only single bonds between carbon atoms.

* Alkenes are hydrocarbons with at least one double bond between carbon atoms.

* Alcohols contain a hydroxyl group (-OH) attached to a carbon atom.

The name "1-nonene" tells us:

* Non indicates a 9-carbon chain.

* Ene indicates the presence of a double bond.

* 1 indicates the position of the double bond (between the first and second carbon atoms).

Since 1-nonene has a double bond, it is classified as an alkene.