Chemistry - GOC Question with Solution | TestHub

The molecules are naphthalene, benzene, thiophene and furan. Resonance energies (kcal/mol): naphthalene 61, benzene 36, thiophene 29, furan 16.

Naphthalene has two fused aromatic rings, so its total resonance energy (61) is larger than that of benzene (36), though it is less than twice 36 because the rings share a bond. Among the five-membered rings, the less electronegative the heteroatom, the better it donates its lone pair into the ring: S (29) $>$ O (16). Benzene, with no heteroatom, is the most stabilised of the single rings.

Order: naphthalene $>$ benzene $>$ thiophene $>$ furan.

Answer: (B).