Question

By how many -CH₂- (methylene) units do the formulae of the first two members of homologous series of alkanes, methane (CH₄) and ethane (C₂H₆) differ? Similarly, by how many -CH₂- units do the neighbouring members ethane (C₂H₆) and propane (C₃H₈) differ from each other?

Answer 1

Methane (CH₄) and ethane (C₂H₆), the first two members of the homologous series of alkanes, differed by one -CH₂- unit. Similarly, there was a -CH₂- unit difference between propane (C₃H₈) and ethane (C₂H₆).