The number of possible aromatic benzenoid isomers for $C_6H_4Cl_2$ are

Which active species is involved in the nitration of benzene with concentrated nitric acid and concentrated sulfuric acid?

Ring nitration of dimethylbenzene results in the formation of only one nitro dimethylbenzene. The dimethylbenzene is

The following compound has four aromatic rings marked as $A$,$B$,$C$ and $D$. Rank them in terms of increasing reactivity towards electrophilic aromatic substitution?

Which of the following are aromatic in character?

Provide basic information about aromatic hydrocarbons. Explain and give examples of the following: $(i)$ Aromatic compounds $(ii)$ Arenes $(iii)$ Benzenoid compounds $(iv)$ Non-benzenoid compounds.