In this case, we need to remember that saturation is a state at which a carbon chain contains no insaturations, that is neither double nor triple bonds such case are alkenes and alkynes, but saturations only which are characterized by the presence of single bonds between adjacent carbon atoms. Such is the case of ethane (CH₃-CH₃), propane (CH₃-CH₂-CH₃), butane (CH₃-CH₂-CH₂-CH₃) and so on.
Fractional distillation is used to separate crude oil into simpler, more useful mixtures . This method can be used because different hydrocarbons have different boiling points