See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Aromaticity Analysis **Hückel's Rule:** A cyclic compound 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) 1,4-Dioxin:** - Contains 2 oxygen atoms with lone pairs in the ring - π electrons: 4 (from two double bonds) = $4(1)+0$ → antiaromatic - Destabilized ✗ **(b) Naphthalene:** - Bicyclic fused system with 10 π electrons = $4(2)+2$ ✓ - Aromatic, but the question asks for a *single* aromatic compound **(c) Cycloheptatriene (7-membered ring with 3 double bonds):** - Contains 6 π electrons = $4(1)+2$ ✓ - Planar structure with continuous conjugation - Satisfies Hückel's rule → **aromatic** ✓ **(d) Pyrrole (5-membered N-heterocycle):** - Has lone pair on N (not in conjugation with π system) - Only 4 π electrons from the ring itself - Antiaromatic in neutral form ✗ **Answer: (c)** — Cycloheptatriene is aromatic because it contains exactly 6 π electrons, fulfilling Hückel's $(4n+2)$ criterion with $n=1$, and maintains planarity necessary for aromaticity.