Concept:Potassium trioxonitrate (V), KNO3, is a soluble salt obtained from its solution by crystallization.Explanation:KNO3 dissolves easily in water.To recover the salt as a solid, the solution is first concentrated by heating or evaporation.The hot concentrated solution is then allowed to cool slowly.On cooling, crystals of KNO3 form and separate from the remaining liquid.This technique of forming crystals from a solution is known as crystallization.Answer:C. crystallization