Question

What is a homologous series? Which two of the following organic compounds belong to the same homologous series?
$C_2{H}_6,C_2{H}_{6}O,C_2{H}_6{O}_2,C{H}_{4}O$

Answer 1

a homologous series is a series of compounds with the same functional group and similar chemical properties in which each successive member differs by ${CH}_2$.Compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties. The name "homologous series" is also often used for any collection of compounds that have similar structures or include the same functional group, such as the general alkanes (straight and branched), the alkenes (olefins), the carbohydrates, etc.

Here, ${CH}_{4}O$ and $C_2{H}_{6}O$ are of same homologous series. Both are differed by ${CH}_2$.