The IUPAC name for
a. the numbering should be such that all the substituents get the least numbering possible.
b. out of the substituents –Cl, -NO2 and –CH3 , nitro group (-NO2 ) gets the priority, meaning nitro benzene is the parent compound and rest are substituents.
c. Least possible numbering is possible only when the carbon with –Cl is designated position one, then the carbon with -NO2 is given two and the carbon with –CH3 is given four.
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