Question

Which amongst the following is not a characteristic of the homologous series?

• A. The members of a homologous series can be represented by a general formula.
• B. Successive members of a homologous series differ by a ${\text{CH}}_3$ group.
• C. The members of a homologous series show a similarity in chemical properties.
• D. The physical properties in the series of compounds have a regular gradation.

Answer 1

The correct option is B Successive members of a homologous series differ by a ${\text{CH}}_3$ group.

The characteristics of homologous series are:

(1) The members can be represented by the same general formula. For example, ${\text{C}}_n{\text{H}}_{2n}$ for alkenes.

(2) Successive member differs by a ${\text{CH}}_2$ group and not by a ${\text{CH}}_3$ group.

(3) Members show similarity in chemical properties.

(4) There is a regular gradation in physical properties. For example, in alkanes as 'n' value increases, their boiling point increases.