Identify the models that represent a mixture of two compounds

If you are referring to the picture then read below:

A compound is a combination of two or more elements that are chemically bounded. A mixture is a combination of two or more substances that are not chemically bounded. Now as you can see in the picture, the model that is boxed show a mixture of two compounds.

The spheres stuck together show different colors, these indicate different elements. These is what makes these compounds. AS you can see the two compounds are not chemically bounded or attached, which shows that collectively, the picture is a mixture.