What distinguishes an unsaturated solution from a saturated solution?

An unsaturated solution is characterized by its ability to dissolve more solute. In this type of solution, the concentration of the solute is lower than its maximum solubility at a given temperature, meaning that there are still solvent molecules available to interact with additional solute particles. This allows for more solute to be added without causing precipitation.

In contrast, a saturated solution has reached the maximum amount of solute that can be dissolved in the solvent at that specific temperature, which is why it cannot dissolve any more solute. The other options do not accurately distinguish unsaturated solutions from saturated ones. For example, while an unsaturated solution does not contain no solute, it certainly holds less than what it is capable of dissolving. Additionally, temperature can influence solubility but is not a defining characteristic that distinguishes unsaturated from saturated solutions. Hence, the defining feature of an unsaturated solution is that it can still dissolve more solute.