Arrange the following in the increasing order of ease of nucleophilic substitution reaction
Chlorobenzene (I) 2,4,6 trinitrochlorobenzene (II) 2,4 dinitro- chlorobenzene (III) and 4- nitrochlorobenzene (IV)

Explanation

As the number of electron-withdrawing `NO_(2)` groups increases at o- and p-positions, the stability of the intermediate carbanion increases and hence reactivity towards nucleophilic substitution increases in the same order, i.e., Chlorobenzenelt4-chloronitrobenzenelt2,4-dinitrochlorobenzenelt2,4,6 trinitrochlorobenzene.