See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Aromaticity To determine aromaticity, apply **Hückel's Rule**: A cyclic species is aromatic if it has $(4n + 2)$ π electrons (where $n = 0, 1, 2, ...$) and is planar with continuous p-orbital overlap. ## Evaluating Each Option: **(A) Benzene** — 6 π electrons = $4(1) + 2$ ✓ Aromatic (planar, conjugated) **(B) Furan** — 5-membered ring with oxygen. Oxygen contributes 2 lone pair electrons + 2 π electrons from C=C bonds = 6 π electrons total. ✓ Aromatic **(C) Cyclopropenyl cation** — 3-membered ring with positive charge. Contains 2 π electrons = $4(0) + 2$ ✓ Aromatic (highly strained but aromatic) **(D) 2-Cyclohexenone** — This is a **6-membered ring with one C=O and one C=C double bond**, giving only **4 π electrons**. Since $4 \neq 4n + 2$ for any integer $n$, this fails Hückel's Rule. Additionally, the sp² hybridized oxygen is **sp² hybridized (not sp)**, breaking the required continuous p-orbital overlap for aromaticity. ✗ **Non-aromatic** ## Answer: **(D) is non-aromatic** because it contains only 4 π electrons, which does not satisfy Hückel's rule $(4n + 2)$, and the conjugation is interrupted.