Chemistry - GOC Question with Solution | TestHub

In (a), due to the presence of $(4n+2)\pi e^{-}$ it follows Huckel's rule and therefore, it is aromatic. In (b), due to the presence of extra lone pair of electrons, total $e^{-}$comes out to be $4\pi e^{-}$. Thus, it is anti-aromatic. In (c), although it is cyclic and has conjugated $8\pi e^{-}$but Huckel's $(4n+2)\pi$ rule is not followed and also ring is not planar. Hence, it is nonaromatic. In $(\mathrm{d})$, it has $6\pi e^{-}$in conjugation but not in the ring, hence it is non-aromatic.