Final answer:
The compound with a CH3CH2CH2CCHCH3 backbone, an O atom double-bonded to the fourth carbon, and a CH3 group on the fifth carbon is named 4-methylpentan-2-one by IUPAC nomenclature.
Step-by-step explanation:
The structure described is an organic molecule with five carbons in the main chain, a double bond to an oxygen atom on the fourth carbon, and an attached methyl group on the fifth carbon. To give the IUPAC name, we need to identify the main functional groups, and the longest carbon chain, and assign the correct locants to the substituents.
Considering the features described, the molecule is a ketone due to the presence of a carbonyl group (C=O) on the fourth carbon. The longest chain containing the carbonyl group has five carbons, making it a pentanone. Since the carbonyl group is on the second carbon from the right (or the fourth carbon from the left), the compound is a 4-pentanone. Additionally, there is a methyl group on the third carbon, denoted by the prefix 'methyl' and its position on the chain.
The IUPAC name of the compound is therefore 4-methylpentan-2-one.