Which of the following species participates in the sulphonation of the benzene ring?

The addition of $Cl_2$ to benzene in the presence of $AlCl_3$ is an example of:

Which of the following compounds will undergo electrophilic substitution more readily than benzene?

Which of the following represents a Friedel-Crafts reaction?

The compound '$A$' with molecular formula $C_8H_{10}$ (aromatic) which gives $1$ mononitro substituted product and $3$ dinitro substituted products is:

Which of the following reactions is correct?