Question

$\qquad ^{+}O-H$

Answer 1

The cyclic system is aromatic due to the presence of 6 $\pi$ electrons in a planar, conjugated ring.

Answer 2

The given structure depicts a six-membered ring containing two double bonds and a negative charge, with a protonated carbonyl group ($=\text{O}^+ \text{H}$) attached to one of the ring carbons. The two double bonds contribute 4 $\pi$ electrons to the ring system. The negative charge, if delocalized into the ring, contributes an additional 2 $\pi$ electrons. Thus, the cyclic system has a total of $4 + 2 = 6$ $\pi$ electrons. According to Hückel's rule, a planar, cyclic, conjugated system with $4n+2$ $\pi$ electrons is aromatic. In this case, $4n+2 = 6$, which means $n=1$. Therefore, if the ring is planar, the species is aromatic, exhibiting enhanced stability. The protonated carbonyl group is a resonance contributor, with the positive charge residing on the oxygen atom. The negative charge is delocalized within the ring, contributing to the aromatic character.