Dichlorobenzene

There are three distinct chemical compounds which are dichlorobenzenes:
 * 1,2-Dichlorobenzene or ortho-dichlorobenzene;
 * 1,3-Dichlorobenzene or meta-dichlorobenzene;
 * 1,4-Dichlorobenzene or para-dichlorobenzene.

All three isomers are colorless chlorobenzenes with the formula C$6$H$4$Cl$2$. They differ structurally based on where the two chlorine atoms are attached to the ring.