Chapter 3 - Section 3.1 - Classification of Matter - Figure 3.3 - Page 59: 1

Physical methods can be be used to separate mixtures but not compounds.

This is due to the fact that substances in a mixtures are physically mixed with each other, therefore, they can be separated by physical methods. On the other hand elements in a compound are chemically bonded to each other, so they can not be separated physically.