The compound prepared by a substitution reaction of benzene is

Aromaticity is present in

Which of the following sets contains only aromatic compounds?

How many isomers are formed when a disubstituted benzene is produced from a monosubstituted benzene?

$n-hexane$ $\xrightarrow{\text{catalyst}}$ benzene
The catalyst is:

Which order is correct for the decreasing reactivity toward ring monobromination of the following compounds:
$I. \, C_6H_5CH_3$
$II. \, C_6H_5COOH$
$III. \, C_6H_6$
$IV. \, C_6H_5NO_2$