Arrange the following in increasing order of reactivity towards aromatic nucleophilic substitution reaction.

Options

A. I `lt` IV `lt` III `lt` II
B. IV`lt` III `lt` I `lt` II
C. I `lt` IV `lt` II `lt` III
D. IV`lt` I `lt` II `lt` III

Answer

B

Explanation

Aromatic nucleophilic substitution in halbarenes can occur when strong electron withdrawing groups are present at ortho or para position to the halogen atom attached to the nucleus. (II) is the most reactive due to presence of two-`NO_2` groups at ortho and para positions, and (IV) is the least reactive due to lack of resonance activation by nitro group from meta position. (I) is more reactive than (III) due to less steric hindrance and greater electrophilicity at `alpha`-carbon of p-fluoronitrobenzene.