Here's why:

* Pure Compound: A pure compound is made up of only one type of molecule. In the case of chloroform, it's a single molecule consisting of one carbon atom, one hydrogen atom, and three chlorine atoms (CHCl₃).

* Mixture: A mixture is made up of two or more substances that are not chemically bonded. They can be separated by physical means.

Since chloroform has a fixed chemical formula and consists of only one type of molecule, it is considered a pure compound.