Question

. Which of the following belong to the same homologous series: ${\mathrm{C}}_3{\mathrm{H}}_4$, ${\mathrm{C}}_3{\mathrm{H}}_6$, ${\mathrm{C}}_4{\mathrm{H}}_8$, ${\mathrm{C}}_4{\mathrm{H}}_6$?

Answer 1

Part 1: Definition of homologous series

1. A homologous series may be defined as a group of organic compounds consisting of the same functional group.
2. Each member of a homologous series differs from the other by a $-{\mathrm{CH}}_2$ group.
3. The chemical properties of all the members of a homologous series are the same.
4. A member of any homologous series is known as a homologue.

Part 3: Identification of homologous series

1. ${\mathrm{C}}_4{\mathrm{H}}_6$ (Butyne) and ${\mathrm{C}}_3{\mathrm{H}}_4$ (Propyne) differ from each other by a $-{\mathrm{CH}}_2$ group and they belong to the alkyne homologous series.
2. ${\mathrm{C}}_4{\mathrm{H}}_8$ (Butene) and ${\mathrm{C}}_3{\mathrm{H}}_6$ (Propene) differ from each other by a $-{\mathrm{CH}}_2$ group and they belong to the alkene homologous series.

Part 4: Final answer

1. ${\mathrm{C}}_4{\mathrm{H}}_6$ (Butyne) and ${\mathrm{C}}_3{\mathrm{H}}_4$ (Propyne) belong to the alkyne homologous series.
2. ${\mathrm{C}}_4{\mathrm{H}}_8$ (Butene) and ${\mathrm{C}}_3{\mathrm{H}}_6$ (Propene) belong to the alkene homologous series.