See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Heat of Hydrogenation Analysis **Understanding Heat of Hydrogenation:** Heat of hydrogenation measures the energy released when $H_2$ adds across a double bond. Higher heat release indicates greater unsaturation/strain energy in the starting material. **Analyzing Option (A):** - **Left compound:** Benzene ($C_6H_6$) — aromatic ring with resonance stabilization - **Right compound:** Cyclohexene — simple alkene with one C=C double bond **Key Comparison:** Benzene has exceptional stability due to: - Resonance delocalization of $\pi$ electrons across all 6 carbons - Aromatic character reduces actual double bond energy - Heat of hydrogenation is **only ~49 kJ/mol** Cyclohexene has: - Localized C=C double bond - No resonance stabilization - Heat of hydrogenation is **~120 kJ/mol** **Conclusion:** Cyclohexene releases significantly more heat upon hydrogenation than benzene because it lacks aromatic stabilization. The $\pi$ electrons in benzene are stabilized by resonance, making them less reactive and releasing less energy when hydrogenated. **Answer: (A) — Cyclohexene gives higher heat of hydrogenation**