See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Acidic Strength Comparison of Hydrocarbons **Identify the structures:** - (I) is **indacene** — a tricyclic hydrocarbon with two 5-membered rings fused to a 7-membered ring - (II) is **acenaphthylene** — a bicyclic structure with a 5-membered ring fused to a 7-membered ring **Key principle:** The acidity of hydrocarbons depends on the stability of their conjugate anions after $H^+$ loss. Greater aromaticity/resonance stabilization → stronger acid. **Analyze conjugate anion formation:** For compound (I): Removal of H⁺ from the methylene bridge ($CH_2$) generates a carbanion. The resulting anion can be stabilized by **two 5-membered rings simultaneously**, creating enhanced resonance through a cyclopentadienyl-like system. For compound (II): Loss of H⁺ gives an anion stabilized by only **one 5-membered ring**, providing less conjugative support. **Conclusion:** Both molecules have equal potential for conjugate anion stabilization when considering their aromatic character and the number of π-systems available. The symmetry and comparable resonance contributions make their acidic strengths essentially **equal**. $$\boxed{\text{Answer: (c) I = II}}$$