See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the compound. The structure is CH3-CH(OH)-CH2-C(=O)-CH3, a five-carbon chain containing a hydroxyl group and a ketone group. Step 2: Identify the principal characteristic group. In IUPAC nomenclature, ketone (=O, suffix '-one') has higher seniority than alcohol (-OH, suffix '-ol'). Therefore, the ketone is the principal characteristic group and gets the suffix, while hydroxyl is cited as a prefix ('hydroxy') or the ketone could be prefix ('oxo') if alcohol is principal — but since ketone outranks alcohol, ketone takes the suffix '-one'. Step 3: Number the chain to give the principal characteristic group (ketone) the lowest possible locant. Numbering from the end closest to the ketone: C1=CH3 (ketone end), C2=C(=O), C3=CH2, C4=CH(OH), C5=CH3. This gives the ketone at position 2 and the hydroxyl at position 4. Step 4: Construct the name. Parent chain: pentane (5 carbons). Ketone at C2: pentan-2-one. Hydroxy at C4: 4-hydroxy. Full name: 4-Hydroxypentan-2-one. Step 5: Check other options. (a) 2-Hydroxypentan-4-one would place the ketone at C4 and OH at C2 — this violates the rule of giving the principal group the lowest locant (ketone should be at C2, not C4). (c) 4-oxopentan-2-ol uses 'oxo' as prefix and 'ol' as suffix, implying alcohol outranks ketone, which is incorrect. (d) 2-oxopentan-4-ol similarly incorrectly prioritizes alcohol over ketone. Therefore, the correct answer is B.