Arrange the compounds in increasing order of rate of reaction towards nucleophilic substitution.

1. (iii) < (ii) < (i) 

2. (ii) < (iii) < (iii) 

3. (i) < (iii) < (ii) 

4. (i) <(ii) < (iii) 

Presence of electron withdrawing group at ortho and para position facilitate the

nucleophilic substitution reaction and trence, enhances rate of reaction.

Compound (iii) has three electron withdrawing groups at ortho and para positions wrt

chlorine while compound (ii) has only one electron withdrawing group and there is no

electron withdrawing group in compound (i). So, the increasing order of rate of reaction

towards nucleophilic substitution is (i)) < (ii) < (iii).