Question

The members of homologous series beginning with the compound $H-CH=C{H}_{2}$ is:
A. $C{H}_{2}=C{H}_{2}$
B. $C{H}_{3}CH=C{H}_{2}$
C. $C{H}_{3}C{H}_{2}CH=C{H}_{2}$
D. All of the above

Answer 1

Hint: Homologous series of compounds is referred to as the series of compounds that have the same general formula but differ from adjacent members by $-C{H}_{2}-$ group. They are determined by the hydrocarbon chain.

Complete step by step answer:
The homologous group of compounds are like alkanes, alkenes, alkynes, etc. The alkanes only have carbon atoms that are attached to the other carbon atoms through single bonds. In alkenes, the carbon atoms are connected through at least one double bond and the rest might or might not be single bonds.

In alkynes, the carbon atoms are connected through at least one triple bond and the rest might or might not be single bonds. The homologous group of compounds have the same general formula.

In the question, the compound that is given is an alkene whose general formula is ${C}_{n}{H}_{2n}$, where n is the no. of carbon atoms. Let us now look at each one of them.
$C{H}_{2}=C{H}_{2}$: It is ethene and has the molecular formula ${C}_{2}{H}_{4}$. It is the same compound which is given in the question. And since its molecular formula matches the general formula, it is a member of the alkene homologous series.

$C{H}_{3}CH=C{H}_{2}$: It is prop-1-ene and has the molecular formula ${C}_{3}{H}_{6}$. And since its molecular formula matches the general formula, it is also a member of the alkene homologous series.

$C{H}_{3}C{H}_{2}CH=C{H}_{2}$: It is but-1-ene and has the molecular formula ${C}_{4}{H}_{8}$. And since its molecular formula matches the general formula, it is also a member of the alkene homologous series.

Therefore, from above, we can say that all of the compounds are the members of the alkene homologous series. Hence, the correct answer is option (d).

Note: If the double bond is shifted to different positions in a carbon atom, the compounds formed have different structures which are known as isomers. These are the compounds that have the same molecular formula but differ in spatial arrangements. They also belong to the same homologous series.