Here's why:

* Hydrocarbons are compounds made of only hydrogen and carbon.

* Substituted hydrocarbons are hydrocarbons where one or more hydrogen atoms have been replaced by other atoms or groups.

* Halogenated hydrocarbons are a specific type of substituted hydrocarbon where one or more hydrogen atoms have been replaced by halogen atoms, like chlorine, bromine, fluorine, or iodine.

Therefore, chlorine can be found in halogenated hydrocarbons.

Let me know if you'd like more details about specific examples of halogenated hydrocarbons!