Question

Which of the compounds ${\mathrm{C}}_2{\mathrm{H}}_6{\mathrm{O}}_2,{\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O},{\mathrm{C}}_2{\mathrm{H}}_6,{\mathrm{CH}}_4\mathrm{O}$ could belong to the same homologous series.

Answer 1

Homologous series of compound lies in the same family and the molecular formula is different by one ${\mathrm{CH}}_2$ unit.

That is, if a compound adds or subtracts by one unit of ${\mathrm{CH}}_2$ from that compound then it is a homologous compound.

The homologue of Methanol $\left({\mathrm{CH}}_4\mathrm{O}\right)$ or $\left({\mathrm{CH}}_3\mathrm{OH}\right)$ compound is by adding one unit of ${\mathrm{CH}}_2$ to give Ethanol $\left({\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}\right)$ or $\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\right)$.

$$\begin{gathered} {\mathrm{CH}}_4\mathrm{O}+{\mathrm{CH}}_2\to {\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O} \\ \mathrm{Methanol}\mathrm{Ethanol} \\ (\mathrm{lower}\mathrm{homologue})(\mathrm{higher}\mathrm{homologue}) \end{gathered}$$

Hence, $\left({\mathrm{CH}}_4\mathrm{O}\right)$ and $\left({\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}\right)$ are homologous to each other.