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Increasing order of electrophilic substitution for following compounds :
A
IV < I < II < III
B
III < II < I < IV
C
I < IV < III < II
D
II < III < I < IV
Detailed Solution
Groups that donate electrons to the ring increase its reactivity towards electrophiles; groups that withdraw electrons decrease it.
$-CF_3$ is a strong electron withdrawing group ($-I$ effect of three F atoms), so benzotrifluoride (IV) is less reactive than benzene.
$-CH_3$ donates electrons by +I effect and hyperconjugation, so toluene (II) is more reactive than benzene (I).
$-OCH_3$ donates electrons strongly by resonance (+R effect), so anisole (III) is the most reactive.
Increasing order: IV $\lt$ I $\lt$ II $\lt$ III.
$-CF_3$ is a strong electron withdrawing group ($-I$ effect of three F atoms), so benzotrifluoride (IV) is less reactive than benzene.
$-CH_3$ donates electrons by +I effect and hyperconjugation, so toluene (II) is more reactive than benzene (I).
$-OCH_3$ donates electrons strongly by resonance (+R effect), so anisole (III) is the most reactive.
Increasing order: IV $\lt$ I $\lt$ II $\lt$ III.