Chemistry - GOC Question with Solution | TestHub

An aromatic compound must be planar, cyclic, fully conjugated, and contain $(4n+2)\pi$ electrons (Hückel's Rule). The 5 aromatic compounds from the given list are:

Benzene: Cyclic, planar, completely conjugated with $6\pi$ electrons ($n=1$).

Naphthalene: Bicyclic, planar, completely conjugated with $10\pi$ electrons ($n=2$).

Ethylbenzene: Contains an aromatic benzene ring core with $6\pi$ electrons.

Borazine ($B_3{N}_3{H}_6$): Inorganic benzene, isoelectronic with benzene, containing $6\pi$ electrons.

Boroxine ($B_3{O}_3{H}_3$): Cyclic system with $6\pi$ electrons from oxygen lone pairs delocalized into boron's empty p-orbitals.

The remaining structures are non-aromatic or anti-aromatic due to missing conjugation or having $4n\pi$ electrons.