See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Carbocation Stability **Step 1: Identify the cations** - **I:** $CH_3\overset{+}{C}HCH_3$ — secondary carbocation (2° allylic) - **II:** $CH_3\overset{+}{C}HOCH_3$ — secondary carbocation with oxygen (2° with resonance) - **III:** $CH_3\overset{+}{C}HCOCH_3$ — secondary carbocation with carbonyl (2° with resonance) **Step 2: Apply resonance stabilization rules** Both II and III have electron-donating groups attached to the carbocation center: - **Oxygen (II):** Highly electronegative, donates electron density via lone pairs → strong resonance stabilization - **Carbonyl carbon (III):** Electron-withdrawing through σ-bonds (inductive effect dominates resonance) → weaker stabilization **Step 3: Rank stability** $$\text{II} > \text{I} > \text{III}$$ - **II is most stable:** Oxygen's lone pairs provide strong +R (mesomeric) effect - **I is intermediate:** Secondary carbocation with only alkyl group hyperconjugation - **III is least stable:** Carbonyl group withdraws electrons inductively more than it stabilizes via resonance **Answer: (b) II > I > III** ✓ The oxygen-stabilized cation (II) is most stable due to the electron-donating resonance effect, while the carbonyl group (III) destabilizes the carbocation through its electron-withdrawing inductive effect.