An unsaturated hydrocarbon that has a double bond is:

C3H6 is called propene, which is an unsaturated hydrocarbon containing a carbon-carbon double bond. It belongs to the alkene family, a group of compounds that all have at least one double bond (C=C) between carbon atoms. The general formula for alkenes is CnH2n, where n is the number of carbon atoms, and for propene, n=3. Alkenes like propene are generally more reactive than alkanes because of the double bond, which can easily take part in chemical reactions.