How will you convert benzene into 

(i) p-nitrobromobenzene 

(ii) m-nitrochlorobenzene 

(iii) p-nitrotoluene

(iv) acetophenone ?

(i) The two substituents in the benzene ring present at p-positions. Therefore, the sequence of reactions should be such that first an o, p-directing group, i.e., Br atom should be introduced in the benzene ring and this should be followed by nitration. Thus, 

(ii) Here, since the two substituents are at m-position w.r.t. each other, therefore, the first substituent in the benzene ring should be a m-directing group (i.e., NO₂) and the other group (i.e., Cl) should be introduced. Therefore, the sequence of reaction is : 

(iii) Here, since the two substituents are at p-position w.r.t. each other, therefore, the first substituent in the benzene ring should be a o, p-directing group (i.e., CH₃) and then the other group (i.e., NO₂) should be introduced.

(iv)  Acetophenone can be prepared by F.C. acylation using either acetyl chloride or acetic anhydride