See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the parent chain. The molecule is CH3-CH(Cl)-CH(Br)-CH(OH)-CH3, which is a 5-carbon chain, so the parent chain is pentane. Step 2: Identify the principal characteristic group. In IUPAC 2013 recommendations, -OH (alcohol) is the principal characteristic group and gets the lowest possible locant as a suffix. The other substituents (Cl, Br) are cited as prefixes in alphabetical order. Step 3: Number the chain to give the principal characteristic group (-OH) the lowest locant. Numbering from the right: the -OH is on C2, -Br is on C3, -Cl is on C4. Numbering from the left: -Cl is on C2, -Br is on C3, -OH is on C4. To give -OH the lowest locant, we number from the right, giving -OH the locant 2. Step 4: Assign locants with right-to-left numbering: - C1: CH3 - C2: CH-OH (hydroxyl at C2) - C3: CH-Br (bromo at C3) - C4: CH-Cl (chloro at C4) - C5: CH3 Step 5: Construct the name. Principal group suffix: -ol at position 2 → pentan-2-ol. Prefixes in alphabetical order: bromo (C3), chloro (C4). Full name: 3-Bromo-4-chloropentan-2-ol. Step 6: Evaluate options. (a) 3-Bromo-4-chloropentan-2-ol — matches our derivation. Correct. (b) 3-Bromo-2-chloro-4-hydroxypentane — incorrectly treats -OH as a prefix (hydroxy) rather than the principal characteristic group suffix. Incorrect. (c) 3-Bromo-2-chloropentane-4-ol — uses the wrong numbering direction, placing -OH at C4 instead of C2, violating the lowest-locant rule for the principal group. Incorrect. (d) none of these — eliminated since (a) is correct. Therefore, the correct answer is A.