A solution that contains less solute than a saturated solution does and that is able to dissolve additional solute.

• A. Colloids
• B. Unsaturated solution
• C. Saturated solution
• D. Supersaturated solution

Answer: (B)

The main idea here is how solubility limits work at a given temperature. If a solution holds less solute than the maximum amount that can be dissolved, it is unsaturated—there is room for more solute to dissolve. So this type of solution can still dissolve additional solute until it reaches the saturation point.

Colloids are mixtures with particles dispersed throughout a medium, not true solutions defined by a solubility limit. A saturated solution already has as much solute as the solvent can hold at that temperature, so it can’t dissolve more under the current conditions. A supersaturated solution contains more dissolved solute than is normally possible at that temperature, which is an unstable state that can precipitate or crystallize suddenly.