question_answer 85)

  (A) Nitration of benzene with nitric acid requires the use of concentrated sulphuric acid. (R) The mixture of concentrated sulphuric acid and concentrated nitric acid produces the electrophile, \[NO_{2}^{+}\].

Answer:

  (a) Conc. \[{{H}_{2}}S{{O}_{4}}\]is used with nitric acid in the electrophilic nitration because it helps to produce nitronium ion\[(NO_{2}^{+})\] electrophile.