#### The first member of alkyne homologous series is (a) ethyne (b) ethene (c) propyne (d) methane

Solution:

A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by $CH_2$ group.

The general formula of alkyne is $C_nH_{2n-2}$ where n is the number of carbon atoms. The first member of alkyne homologous series is ethyne $C_2H_2$ as you need 2 carbons minimum to have a carbon connected with double bond.

Therefore, option (a) is correct.