What is meant by homologous series of carbon compounds ? Write the general formula of (i) alkenes, and (ii) alkynes. Draw the structures of the first member of each series to show the bonding between the two carbon atoms.

Explanation

A homologous series is a series of organic compounds that belongs to the same family (i.e., possesses the same functional group) and show similar chemical properties. The members of this series are called homologous, they differ from each other by the number of `CH_(2)` units in the main Carbon chain.
General Formula
Alkenes : `C_(n)H_(2n)`, Alkynes : `C_(n)H_(2n-2)`
Structures
The first member of alkenes is ethene and its structure is given below.
`H-underset(H)underset(|)(C )=overset(H)overset(|)(C )-H`
The first member of alkenes is ethene and its structure is given below.
`H - C -= C- H`