See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Resonance Energy Comparison **Resonance energy** reflects the stabilization gained from electron delocalization. Lower resonance energy means less stabilization through resonance. ## Analysis of Each Pair: **(A) $CO_3^{2-}$ vs $HCOO^-$** - Both are conjugated systems with resonance - $CO_3^{2-}$: Three equivalent resonance structures (high stability) - $HCOO^-$: Two resonance structures (lower stability than $CO_3^{2-}$) - Both have significant resonance energy **(B) Cyclopropene cation vs Allyl cation ($CH_2=CH-CH_2^+$)** - Cyclopropene cation: 2 resonance structures (aromatic stabilization via 3-membered ring) - Allyl cation: 2 resonance structures (good delocalization) - Both have notable resonance stabilization **(C) Cyclopropene vs Butadiene ($CH_2=CH-CH=CH_2$)** - **Cyclopropene**: Single C=C double bond in a 3-membered ring - Ring strain prevents effective conjugation/resonance - Minimal resonance contribution - **Butadiene**: Extended conjugation with multiple resonance structures - Two allylic resonance forms provide significant stabilization - **Cyclopropene has much less resonance energy** ✓ **(D) Cyclopropene cation vs Allyl cation** - Both conjugated species with resonance stabilization - Both have appreciable resonance energy **Answer: (C)** — Cyclopropene lacks the conjugation capacity of butadiene due to ring strain, making it the species with **least resonance energy** in its pair.