What is the correct decreasing order of the percentage of the para -isomer in the product mixture when the following compounds undergo electrophilic bromination with Br ₂ / FeBr ₃ ? I. II. III.

Step-by-step solution

The percentage of the para -isomer in the product mixture depends on the directing nature and the steric bulk of the substituent present on the benzene ring. In compound II (nitrobenzene), the - NO ₂ group is strongly deactivating and meta-directing. Electrophilic bromination will predominantly yield the meta -isomer, making the para -isomer a minor/trace product. Thus, it has the lowest percentage of the para -isomer. Both compound I (toluene) and compound III ( tert -butylbenzene) have alkyl groups, which are act