See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the parent chain: Locate the carbonyl group (C=O) and find the longest continuous carbon chain that includes it. The structure shows: CH3-CH(CH3)-C(=O)-CH2-CH(CH3)-CH2-CH3. Counting all carbons in the longest chain through the carbonyl: C1(CH3)-C2(CH3 branch)-C3(C=O)-C4(CH2)-C5(CH branch)-C6(CH2)-C7(CH3), giving a 7-carbon chain (heptane). Step 2 - Name the parent chain with ketone suffix: The carbonyl is at C3, so the parent is heptan-3-one. Step 3 - Identify substituents: At C2, there is a methyl group (from the isopropyl-like arrangement on the left side). At C5, there is a methyl group (from the sec-butyl-like arrangement on the right side). Step 4 - Apply numbering to give lowest locants: Numbering from the left gives the carbonyl at C3 and methyl groups at C2 and C5 (locant set: 2,3,5). Numbering from the right gives carbonyl at C5 and methyls at C3 and C6 (locant set: 3,5,6). The left-to-right numbering gives lower locants, confirming C2 and C5 for the methyl substituents and C3 for the ketone. Step 5 - Compile the name: Two methyl substituents at positions 2 and 5, ketone at position 3 of heptane → 2,5-dimethylheptan-3-one. Therefore, the correct answer is 2,5-dimethylheptan-3-one.