Question

Which of the following belong to a homologous series?
1. $HCOOH$
2. $C{H}_{3}COOH$
3. $C_2{H}_6$
4. $C_2{H}_{5}COOH$
5. $C_3{H}_6$

• A. 1, 2 and 5
• B. 1, 3 and 4
• C. 1, 2 and 4
• D. 1, 2 and 3

Answer 1

The correct option is C 1, 2 and 4

A homologous series is a series of compounds in which each member differ from the previous/next member by $C{H}_2$ or 14 mass units and have the same functional group.
1, 2 and 4 have same functional group (-COOH), so they are homologous in nature. $C_2{H}_6$ and $C_3{H}_6$ are neither homologous with 1, 2 and 4 nor with each other.