There are three isomers of dichlorobenzene, one of which has now replaced naphthalene as the main constituent of mothballs.

a. Identify the ortho, the meta, and the para isomers of dichlorobenzene.

b. Predict the number of isomers for trichlorobenzene.

c. It turns out that the presence of one chlorine atom on a benzene ring will cause the next substituent to add ortho or para to the first chlorine atom on the benzene ring. What does this tell you about the synthesis of m-dichlorobenzene?

d. Which of the isomers of trichlorobenzene will be the hardest to prepare?