Question

The formula for the members of homologous series beginning with acetone $C{{H}_{3}}COC{{H}_{3}}$ is:
A. $C{{H}_{3}}-CO-C{{H}_{2}}-C{{H}_{3}}$
B. $C{{H}_{3}}-CH(OH)-C{{H}_{3}}$
C. $C{{H}_{3}}-O-C{{H}_{3}}$
D. $C{{H}_{3}}-C{{H}_{2}}-O-C{{H}_{3}}$

Answer 1

Hint: Homologous series is defined as the series of those compounds which have similar chemical properties and some functional group which differ from the successive member by $C{{H}_{2}}$ group. Carbon chains of varying length have been observed in organic compounds which have the same general formula.

Complete answer:
Organic compounds which are different from one another by a repeating unit and these types of compounds generally have the same chemical formula. These formula can be differentiated on the types of compounds like for Alkanes those compounds which do not have unsaturation have the $C{{H}_{3}}-CO-{{C}_{5}}{{H}_{11}}$ ${{C}_{n}}{{H}_{2n+2}}$ alkenes which having double bond have general formula ${{C}_{n}}{{H}_{2n}}$ and alkynes having triple bond have general formula ${{C}_{n}}{{H}_{2n-2}}$these compounds form the most basic homologous series in organic chemistry.
Now the compound given in the question is acetone represented by the chemical formula $C{{H}_{3}}COC{{H}_{3}}$ this compound is kept in the category of ketones whereas ketones are those compounds which have $CO$ group in them and have the suffix one in them.
The formula for the members of homologous series beginning with acetone $C{{H}_{3}}COC{{H}_{3}}$ is as following:
1. $C{{H}_{3}}COC{{H}_{3}}$
2. $C{{H}_{3}}-CO-C{{H}_{2}}-C{{H}_{3}}$ known by the name Butan2-one
3. $C{{H}_{3}}-CO-C{{H}_{2}}-C{{H}_{2}}-C{{H}_{3}}$ known as Pentan-2-one
4. $C{{H}_{3}}-CO-{{C}_{4}}{{H}_{9}}$ known as Hexan-2-one
5. $C{{H}_{3}}-CO-{{C}_{5}}{{H}_{11}}$ known as Heptan-2-one

Hence from this we can see that option A is the correct answer.

Note:
This series can predict the properties of organic compounds belonging to a particular homologous series based on the data available from the other members of the same series. The study of organic compounds has been simplified by this series.