Question

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Answer 1

3. Benzene can be converted to n-propyl benzene by using two different reagents.

In the first step, benzene is converted to phenyl ethyl ketone through Friedel-Craft's acylation of propanoyl chloride in presence of anhydrous AlCl3.

In the second step  phenyl ethyl ketone is reduced to n-propyl benzene through Clemmensen's reduction (reagent used is (Zn-Hg/ con.HCl) as shown in the figure below.

4.(A) When electron donating groups like -OCH₃ activate the benzene by donating electron to the benzene ring and hence are the most reactive towards electrophilic aromatic substitution reaction.

Electron withdrawing groups like -Cl, -COCH₃, -CF₃, and -NO2 deactivate the benzene ring by withdrawing electron from the benzene ring. However -Cl is weakly deactivating, -COCH₃, -CF₃ are moderately deactivating and -NO₂ is strongly deactivating. Hence -NO₂ is the least reactive towards electrophilic aromatic substitution reaction.

Hence the order of reactivity is -OCH₃ > -Cl> -CF₃ >-COCH₃  > -NO2

Hence (A) is the correct answer.