Many of the compounds found in commercial preparations are listed by their formal names, and it is essential to be able to interpret them in terms of their structures. Many of these compounds are aromatic or have aromatic regions. Name 

(a) Compound (6) and the three dimethylbenzenes (xylenes), in which the second methyl group is on carbon atom 

(b) 2; 

(c) 3; 

(d) 4.

PLAN Name the compounds by counting around the ring in the direction that gives the smallest numbers to the substituents.