Concept:For IUPAC naming of alkanes, choose the longest continuous carbon chain as the parent and number it so that the substituent gets the lowest possible locant.
Explanation:The longest continuous chain in the structure has
8 carbon atoms, so the parent hydrocarbon is octane.
Number the octane chain from the end nearest the substituent.
An ethyl group,
−CH2CH3, is attached to carbon number
4.
Numbering from the opposite end would give
5-ethyloctane, so the lower locant
4 is preferred.
Naming it as a propylheptane would require choosing a shorter parent chain, which is not allowed by IUPAC rules.
Therefore, the IUPAC name is 4-ethyloctane.
Answer:A. 4-ethyloctane.
