Recall that di-substituted benzenes have three isomers, in that the two substituents may be in ortho-, or para-position relative to each other:

Depending on the nature of the two substituents, the three isomers may have quite similar or very different properties.

Write down all possible tri-substituted benzenes for the following situations (a) all substituents are the same (AAA), (b) only two of the substituents are the same (AAB), (c) all three substituents are different (ABC).

*Problem 2.2 chapter 2,in environmental organic chemistry; Ren P. Shwarzenbach