Chlorine exhibits -I effect, pulling electrons towards itself, thus creating a slight positive charge on the carbon attached. In compound 2, -I effect of chlorine is most pronounced making the compound reactive towards $\mathrm{S}_\mathrm{N} 2$ reaction. In compound 3, -I effect of chlorine is strong but is countered by the resonance effect making substitution possible at $\text{o-, p}$ - positions. In compound 1, -I effect of chlorine is balanced by the $+I$ effect of the cycloalkyl group.