Rate determining step in nitration of benzene is

The nitration of benzene takes places in three steps, i.e.
(1) Generation of electrophile (NO₂)
(ii) Attack of an electrophile to benzene ring forming the carbocation
(iii) Loss of proton from carbocation giving nitrobenzene.
The attack of electrophile to benzene ring giving a carbocation is the slowest and rate determining step.