A mixture containing two salts of different solubility can be separated by

Step 1: Analyze the question We have two dissolved salts with different solubilities. We need a method that exploits the difference in solubility.

Step 2: Review the options

• Chromatography: separates substances by how fast they travel through a medium. It is used mainly for dyes, pigments and amino acids. It works on differences in adsorption and solubility in a solvent, but it is not the standard method for separating salts.
• Crystallization: separates substances by differences in solubility. As a hot saturated solution cools, the less soluble salt crystallizes out first, while the more soluble salt stays in solution. This is called fractional crystallization.
• Distillation: separates liquids with different boiling points, or a solvent from a solute. It does not separate two salts from each other.
• Evaporation: removes the solvent and leaves both salts behind together, so it does not separate them.

Step 3: Solution

1. Dissolve the mixture in hot water to make a saturated solution.
2. Cool the solution slowly.
3. The less soluble salt crystallizes first, and you filter it off.
4. The more soluble salt stays in the filtrate. Evaporating the filtrate further recovers it.

A common example is separating potassium nitrate from sodium chloride. Potassium nitrate's solubility changes greatly with temperature, while sodium chloride's barely changes.

**Answer: B. Crystallization.

Exam tip: When you see "different solubility," think crystallization. Think "different boiling points" for distillation, "insoluble solid in liquid" for filtration, and "dyes or pigments" for chromatography.