Question

$C_3{H}_6,C_4{H}_8$ and $C_5{H}_{10}$ belong to the same homologous series. Define homologous series.

Answer 1

A series of organic compounds each containing a characteristic functional group and the successive members differ from each other in the molecular formula by $-C{H}_2-$ group is called homologous series.

In homologous series, homologues are arranged in the increasing order of their molecular mass.

Characteristics of homologous series :

1. Homologues can be represented by same general formula and functional group.
2. They can be prepared by the same chemical methods.
3. They show similar chemical properties, and gradation in physical properties such as melting point, boiling point, density, solubility, etc.
4. Here, $C_3{H}_6$, $C_4{H}_8$ and $C_5{H}_{10}$ differ by $-C{H}_2-$ group, hence they belong to same homologous series.