Name the method used for preparing insoluble salts.

• A. Titration method
• B. Distillation
• C. Precipitation reaction
• D. Fermentation

Answer: (C)

Insoluble salts are made by a precipitation reaction. When you mix two aqueous solutions containing ions, they can combine to form a new compound that is insoluble in water. That solid appears as a precipitate and can be collected by filtration, then washed and dried to obtain the pure insoluble salt. For example, mixing ions from soluble salts like a metal cation with a suitable counter anion can yield a solid salt that does not dissolve.

The other methods don’t fit this purpose. A titration method is about measuring quantity or concentration by careful reaction with a standard solution. Distillation separates components based on boiling points. Fermentation is a biological process.