Suggest a possible reason for the following observations:
The order of reactivity of haloalkanes is `RIgtRBrgtRCl`.

Explanation

The order of reactivity is : `RIgtRBrgtRClgtRF` On going down the group, size of the halides increases and hence stability of the compound decreases as bond length is going to increase, resulting is easy breakdown of the bond and hence, reactivity increases. Thus, the correct order of reactivity is
`RIgtRBrgtRClgtRF`