Ethene, C2H4, is an example of an unsaturated hydrocarbon. Other examples of unsaturated compounds are benzene, C6H6, and acetic acid, C2H4O2. All bond angles about the carbon-carbon double bond are 120o. All atoms bonded to the double bonded carbon atoms lie in the same plane.n unsaturated hydrocarbon is a hydrocarbon containing at least one double or triple bond. An alkene is a hydrocarbon containing double bonds. The general formula of an alkene is CnH2n. An alkyne is a hydrocarbon containing triple bonds. The general formula of an alkyne is CnH2n-2.