See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Carbocation Stability Analysis **Stability factors for carbocations:** - Hyperconjugation (alkyl groups stabilize positive charge) - Resonance stabilization (delocalization of charge) - Number of alkyl groups attached to charged carbon **Analyzing each carbocation:** **(1) Tropylium cation ($C_7H_7^+$):** Aromatic 7-membered ring with aromatic stabilization. **Extremely stable** due to resonance delocalization (Hückel's rule: $4n+2 = 6$ π electrons). **(2) Allyl cation ($CH_2=CH-CH_2^+$):** Secondary carbocation with strong resonance stabilization through delocalization into the π-bond. **Very stable**. **(3) Benzyl cation ($C_6H_5-CH_2^+$):** Primary carbocation but stabilized by resonance with the benzene ring. **Highly stable** (similar to allyl). **(4) Isopropyl cation ($CH_3-CH^+-CH_3$):** Secondary carbocation with only hyperconjugation (no resonance). **Moderately stable**. **Stability order:** $$\text{Tropylium (1)} > \text{Benzyl (3)} \approx \text{Allyl (2)} > \text{Isopropyl (4)}$$ Since (3) ≈ (2), option **(D) states $(3) = (2) > (1) > (4)$**, which correctly reflects that **aromatic tropylium is most stable, then resonance-stabilized carbocations are roughly equivalent, and alkyl carbocations are least stable.**