Assertion (A): When chlorobenzene and benzene are nitrated side by side under the same conditions, chlorobenzene reacts more slowly, so the chlorine atom deactivates the ring towards electrophilic substitution. Reason (R): In chlorobenzene, resonance with the lone pairs of chlorine puts more electron density at the ortho and para positions than at the meta position, so an incoming electrophile goes mainly to the ortho and para positions.