Chemistry - GOC Question with Solution | TestHub

Removing ${\mathrm{H}}^{+}$ from cyclopentadiene (III) gives the cyclopentadienyl anion (6π, aromatic), so it is by far the most acidic. Cycloheptatriene (I) would give an 8π anti-aromatic anion, cyclohexa-1,3-diene (II) gives an ordinary anion with no aromatic gain, and cyclooctatetraene (IV) would give a 9π anion that is not aromatic. So (III).