Answer : A solution that has reached equilibrium and has undissolved solute remaining in the solution must be, saturated solution.
Explanation :
Unsaturated solution : It is defined as the solution in which more solute particles can be dissolved in the solvent.
Saturated solution : It is defined as the solution in which no more solute particles can be dissolved in the solvent.
As per question, when a solution reached to equilibrium and some amount of undissolved solute remaining in the solution that means no more solute can be dissolved in the solvent then that solution will be saturated solution.
Hence, the solution must be saturated solution.
