International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

Which of the following methods is not typically used for separating components of a liquid mixture?

1. Filtration

2. Crystallisation

3. Simple distillation

4. Dissolving

The correct answer is: Dissolving

Dissolving is not typically used for separating components of a liquid mixture because it involves the mixing of substances to form a solution, rather than separating them. In processes like filtration, crystallization, and simple distillation, physical methods are employed to separate components based on differences in properties such as particle size, solubility, and boiling point. Filtration is effective for separating solids from liquids based on particle size, where solid components are retained, and the liquid passes through a filter. Crystallization allows for the separation of dissolved solids from a solution by forming solid crystals as the solution cools or as solvent evaporates. Simple distillation relies on differences in boiling points to separate liquids, where the component with the lower boiling point vaporizes first and is then condensed back into a liquid. In contrast, dissolving does not create a separation; instead, it results in a homogeneous mixture where the components are uniformly distributed. Thus, it does not serve as a method for separating liquid mixture components, making it the right choice for this question.