In the questions, arrange the compounds in increasing order of the rate of reaction towards nucleophilic substitution.
(i) (a) < (b) < (c)
(ii) (a) < (c) < (b)
(iii) (c) < (b) < (a)
(iv) (b) < (c) < (a)
(iv) The rate of nucleophilic substitution decreases when there is an electron releasing group at ortho or para positions.