The order of reactivities of the following alkyl halides for a SN2 reaction is

N S 2 reaction is the nucleophilic substitution bi- molecular reaction in which the leaving group is substituted by a nucleophile. The reactivity of the alkyl halides towards N S 2 reaction depends on the quality of the leaving group. If the halide is a good leaving group, then the reactivity increases. Now, the strength of the bond between the carbon atom and the halogen decides the quality of the leaving group. If the bond strength is weak then the halogen will be a good leaving group because it can easily break the C – X bond. Now, the larger the size of the halogen, larger will be the bond