In the questions, arrange the compounds in increasing order of the rate of reaction towards nucleophilic substitution.
(i) (a) < (b) < (c)
(ii) (b) < (a) < (c)
(iii) (c) < (b) < (a)
(iv) (a) < (c) < (b)
(c) Electron releasing groups increase the reactivity of aryl halides, less is the number of electron releasing groups,the less is the rate towards nucleophilic substitution.