Final answer:
An unsaturated solution is characterized by a reaction quotient (Q) that is less than the solubility product constant (Ksp), allowing for more solid to dissolve until equilibrium is reached. Option B is the correct answer.
Step-by-step explanation:
When determining the saturation state of a solution, we compare the reaction quotient (Q) with the solubility product constant (Ksp). The Q represents the product of the concentrations of the ions at a given moment and can be compared to the established Ksp value to predict the solubility behavior of the solution.
For an unsaturated solution, Q is less than Ksp. This means that more solid can dissolve in the solution until equilibrium is reached, where Q will be equal to Ksp. If Q were to exceed Ksp, the solution would be supersaturated, and precipitation would occur to restore equilibrium. Thus, for a solution that has not yet reached the saturated state, the correct relationship is Q < Ksp.
Therefore, the correct option that describes an unsaturated solution is b) Q < Ksp.