Final answer:
The sample of matter with 3 different types of atoms that can be physically separated is a heterogeneous mixture.
Step-by-step explanation:
Based on the description that there are 3 different types of atoms within the sample of matter and that they can be physically separated from one another, we can conclude that this sample is a heterogeneous mixture. A heterogeneous mixture is made up of different substances that remain physically separate and can be seen as individual components.
This is different from a homogeneous mixture, in which the composition is uniform and you cannot see individual substances. Furthermore, a pure substance would consist of a single type of atom or molecule throughout, which does not apply in this scenario.