How can you tell a mixture is not a solution?

A mixture is a combination of compounds or substances that can be separated back into individual components by physical methods. A mixture can be homogeneous, where the components are the same throughout, such as a chocolate ice cream. The mixture can also be heterogeneous, where components are non-uniformly mixed. An example is trail mix.

A solution consists of a solute mixed in a solvent, such as sugar in water, etc. A solution can be thought of as a homogeneous mixture where the mixture is a single phase. We can also have a suspension, where the solute and solvent separate, like oil in water, and there would be multiple phases.

Thus, if a mixture has a single phase and is homogeneous, it is a solution. If we observe different phases in a mixture, we can determine the mixture to be not a solution.

Hope this helps.