See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Aromaticity Analysis Using Hückel's Rule **Hückel's Rule:** A planar, cyclic compound with continuous conjugation is aromatic if it contains $(4n + 2)$ π electrons, where $n = 0, 1, 2, ...$ --- ## Analysis of Each Species: **(A) Anthracene (tricyclic aromatic hydrocarbon)** - Central benzene ring shares electrons with two outer rings - Contains $14$ π electrons total - Follows $(4n + 2)$: $14 = 4(3) + 2$ ✓ - **Aromatic** **(B) Indole (benzene + pyrrole fused)** - Benzene ring: $6$ π electrons - Pyrrole ring: $4$ π electrons from $\ce{N}$ lone pair (contributes to aromaticity) - Total: $10$ π electrons = $4(2) + 2$ ✓ - Planar, continuous conjugation - **Aromatic** **(C) Cyclopentadienyl anion ($\ce{C5H5-}$)** - $5$ sp² carbons in a ring with continuous conjugation - Negative charge adds $1$ electron to the $4$ π electrons from double bonds - Total: $6$ π electrons = $4(1) + 2$ ✓ - **Aromatic** --- ## Conclusion: All three structures (A, B, and C) satisfy Hückel's rule and are aromatic species. **Answer: (D) All** — All three compounds are aromatic.