Medium· Aromatic Hydrocarbon (Aromaticity)· +4 / −1
Consider the following compounds/species:
i. Naphthalene (two fused benzene rings)
ii. Cyclopentadienyl anion (five-membered ring with two double bonds and a carbanion bearing a lone pair)
iii. Cyclobutadiene (four-membered ring with two double bonds)
iv. Cyclopropenyl anion (three-membered ring with one double bond and a carbanion with a lone pair)
v. Cyclopropenyl cation (three-membered ring with one double bond and a positive charge)
vi. Cyclooctatetraene (eight-membered ring with four double bonds)
vii. Anthracene (three linearly fused benzene rings)
The number of compounds/species which obey Huckel's rule is ______.