Give reason for the following:
Nitrobenzene, but not benzene, is used as a solvent for the Friedel - Craft alkylation of bromobenzene.

Explanation

Benzene being more reactive than bromobenzene would preferentially undergo alkylation. On the other hand presence of electron withdrawing. `NO_2` group makes nitrobenzene less reactive than bromobenzene and so it will not undergo Friedel-craft reaction.