The difference in molecular mass between two consecutive homologous series members will be:

In a homologous series, each consecutive member differs by a CH2 group, which adds 14 g/mol to the molecular mass. This consistent increase allows compounds in the series to have similar chemical properties while varying in size. For example, in the alkane series, methane (16 g/mol) and ethane (30 g/mol) differ by 14 g/mol. This pattern helps in identifying and classifying organic compounds.