In the given reaction,$C_6H_6 + HNO_3 \xrightarrow{H_2SO_4} C_6H_5NO_2 + H_2O$,$HNO_3$ acts as:

What will be $C$ in the following reaction?
$C_6H_5CH_3$ $\xrightarrow{\text{Oxidation}} A$ $\xrightarrow{NaOH} B$ $\xrightarrow[\Delta]{\text{sodalime}} C$

Total number of aromatic compounds from the following is:

The electrophile used in the sulfonation of benzene is..........

The condition required for an aromatic ring is that it must contain $... \pi-$ electrons.

Give the resonance structures of the $\sigma$-complex formed during the electrophilic aromatic substitution of benzene. Explain the stability of the $\sigma$-complex.