
The depicted reaction is a free radical halogenation. This technique is inappropriate for synthesizing fluoroarenes due to fluorine's extreme reactivity, which impedes reaction control and results in polysubstitution. The free radical in this specific reaction is generated using iron (Fe) metal under dark conditions. For other halogens, the reaction can be managed to yield the desired haloarenes.
The correct order of the rate of reaction of the following reactants with nucleophile by \( \mathrm{S_N1} \) mechanism is:
(Given: Structures I and II are rigid) 