See image — IUPAC and Nomenclature Chemistry Question

💡 Solution & Explanation

Step 1: Identify the structure. The molecule shown is CH2(COOH)-CH2-CH2(COOH), i.e., a three-carbon chain where carbon 2 bears a COOH group and carbon 3 (the terminal carbon) also bears a COOH group. More carefully reading the structure: CH2 — CH2 — CH2 with COOH on the second carbon and COOH on the third carbon. This gives: HOOC-CH2-CH2-CH2-COOH when the COOH groups are counted as part of the parent chain. Step 2: Determine the parent chain. The two carboxylic acid groups (COOH) are at the ends of a chain. When naming dioic acids (alkanedioic acids), the COOH carbons are included in the parent chain. The structure is HOOC-CH2-CH2-CH2-COOH: the two terminal COOH carbons plus the three CH2 carbons in between give a total of 5 carbons in the longest chain containing both acid groups. Step 3: Apply IUPAC nomenclature. A 5-carbon chain with carboxylic acid groups at positions 1 and 5 is named pentane-1,5-dioic acid (also known as glutaric acid). The suffix '-dioic acid' is correct for a dicarboxylic acid where both COOH groups are included in the parent chain count. Step 4: Evaluate options. - (a) Pentane-1,5-dioic acid: correct — 5 carbons total (including both COOH carbons), dioic acid suffix. - (b) Pentane-1,5-dicarboxylic acid: incorrect — 'dicarboxylic acid' suffix would imply the COOH groups are substituents on a pentane chain (which would make it a 7-carbon compound), not the correct IUPAC format here. - (c) Propane-1,3-dioic acid: incorrect — this would be HOOC-CH2-COOH (malonic acid, only 3 carbons total), not matching the given structure. - (d) none of these: incorrect since (a) is correct. Therefore, the correct answer is A.