See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Degrees of unsaturation (DoU) are calculated using the formula DoU = (2C + 2 + N - H - X) / 2, or equivalently by counting all rings and pi bonds in the structure. Step 1: Identify all rings. - Ring 1: Benzene ring (aromatic) — counts as 1 ring + 3 double bonds = 4 DoU - Ring 2: Left fused alicyclic ring (cyclohexane-type fused to benzene on the left) — 1 ring DoU - Ring 3: Right fused alicyclic ring (cyclohexane-type fused to benzene on the right) — 1 ring DoU Total from rings: 3 rings = 3 DoU (ring contributions) Step 2: Identify all pi bonds (double and triple bonds) not already counted in the benzene ring count: - Benzene ring: 3 C=C pi bonds (DoU = 4 total for benzene: 1 ring + 3 pi) - Left alicyclic ring: one C=C double bond = 1 DoU - Right alicyclic ring: one C=C double bond = 1 DoU - Carboxylic acid group (-COOH): one C=O pi bond = 1 DoU - Terminal alkyne side chain (-C≡C-): two pi bonds = 2 DoU Step 3: Sum all DoU: - Benzene (1 ring + 3 pi bonds) = 4 - Left ring (1 ring) = 1 - Right ring (1 ring) = 1 - Left ring C=C = 1 - Right ring C=C = 1 - COOH C=O = 1 - Alkyne (2 pi bonds) = 2 Total = 4 + 1 + 1 + 1 + 1 + 1 + 2 = 11 Step 4: Verify against options. - (a) 6: Too low; misses multiple unsaturations. - (b) 7: Too low; misses the alkyne and several pi bonds. - (c) 10: Off by one; likely misses one pi bond contribution. - (d) 11: Matches the complete count of 3 rings + 3 (benzene pi) + 1 (left ring C=C) + 1 (right ring C=C) + 1 (COOH) + 2 (alkyne) = 11. Therefore, the correct answer is D.