In the following reaction,the catalyst used is:

Benzene can react with..........

The reaction of benzene with a mixture of concentrated $HNO_3$ and concentrated $H_2SO_4$,followed by treatment with $Cl_2 / FeCl_3$,gives:

What are the various steps of electrophilic substitution of benzene?

Deduce the structure of $(A)$.
$(A) \ C_{8}H_{10}$ $\xrightarrow{KMnO_{4}} (B) \ C_{8}H_{6}O_{4}$ $\xrightarrow[Fe]{Br_{2}} C_{8}H_{5}BrO_{4} (C)$ (one-product only)

Which of the following compounds is not aromatic?