CBSE Class 9 Answered

Based on distinct properties, solutions can be classified into True Solution, Suspension and Colloid. Colloidal Solution is a heterogeneous mixture in which particle size of substance is intermediate of true solution and suspension. For example, smoke from a fire in which tiny particles of solid float in air.

The differentiating factor between a true solution and a colloidal solution is essentially the size of the particles. In a true solution, such as salt water, sodium chloride molecules are fully dissolved into water, and the solution can pass through a membrane without becoming separated. In a colloidal solution, on the other hand, the particles are larger and don’t dissolve, but rather become equally dispersed throughout a liquid. As such these particles will not pass through a membrane as the liquid does.