Final answer:
The mixed solvent pair used for recrystallization includes one solvent in which the solute is very soluble and another in which the solute is poorly soluble to insoluble; the correct answer is B) Soluble, Insoluble.
Step-by-step explanation:
When no single solvent seems to work for a recrystallization, a pair of miscible solvents can be used. This mixed solvent pair typically includes one solvent in which the particular solute is very soluble, and another in which its solubility is poor to insoluble. The correct answer to the question is therefore B) Soluble, Insoluble.
The concept of miscibility is based on the axiom "like dissolves like," which indicates that substances with similar polarities are more likely to dissolve in each other. When a solute is soluble in one solvent but not in another, it benefits from a mixed solvent system because the solute can be dissolved selectively and then precipitated by adding the solvent in which it is poorly soluble or insoluble.