Write the IUPAC names of the compounds i-iv from their given structures.
`underset(6)CH_(3)-overset(O)overset(||)underset(5)C-underset(4)CH_(2)-underset(3)CH_(2)-underset(2)CH_(2)-underset(1)COOH`

Explanation

Here, two functional groups namely ketone and carboxylic acid are present. The principal functional group is the carboxylic acid group, hence the parent chain will be suffixed with ‘oic’ acid. Numbering of the chain starts from carbon of – COOH functional group. The keto group in the chain at carbon 5 is indicated by ‘oxo’. The longest chain including the principal functional group has 6 carbon atoms, hence the parent hydrocarbon is hexane. The compound is, therefore, named as 5-Oxohexanoic acid.