Here's why:
* Solutions are homogeneous mixtures where the solute (copper sulfate) dissolves completely into the solvent (water). The particles of the solute are so small that they are evenly distributed throughout the solvent, and the mixture appears clear.
* Suspensions are heterogeneous mixtures where the solute particles are large enough to settle out over time. You can see the separate components of a suspension.
* Colloids are heterogeneous mixtures where the solute particles are larger than those in a solution, but smaller than those in a suspension. They are dispersed throughout the solvent and don't settle out easily.
Since copper sulfate dissolves completely in water and forms a clear, homogeneous mixture, it is classified as a solution.
