Chemistry - GOC Question with Solution | TestHub

Furan (6π), the tropylium cation (6π), pyridine (6π) and the cyclopentadienyl anion (6π) are aromatic. Cyclobutadiene (4π) and the cyclopentadienyl cation (4π) are anti-aromatic, and cyclohexa-1,3-diene has an $\mathrm{s}{\mathrm{p}}^3$ carbon, so it is non-aromatic. The count is 4.