question_answer

                Among the following compounds the decreasing order of reactivity towards electrophilic substitution is :

A)                                                                                                                                                                                                         II > I > III > IV     

B)                 III > I > II > IV     

C)                 IV > I > II > III     

D)                 I > II > III > IV

Correct Answer: B

Solution :

                                In \[-C{{H}_{3}},\,-OC{{H}_{3}}\] and \[C{{F}_{3}},\,C{{H}_{3}}\] and \[-OC{{H}_{3}}\] are electron donating group. Hence, they activate the benzene nucleus. In these, order of activation is \[-OC{{H}_{3}}>-C{{H}_{3}}\] while \[-C{{F}_{3}}\] group deactivates the benzene nucleus. So, it shows lower rate of electrophilic substitution on benzene ring. Thus, order of electrophilic substitution is-