Through inductive effect, chlorine
destabilises the intermediate carbocation formed during the electrophilic
substitution Through resonance, halogen tends to stabilise the carbocation and
the effect is more pronounced at ortho- and para- positions The
inductive effect is stronger than resonance and causes net electron
withdrawal and thus causes net deactivation The resonance effect
tends to oppose the inductive effect for the attack at ortho- and para-
positions and hence makes the deactivation less for ortho- and para-
attack