How can you distinguish between a true solution and a colloidal solution by a simple physical process in the laboratory? Mention an industrial application of a physical property of the colloidal system which is used in the above process.

Explanation

Tyndall effect can be used to distinguish between a true solution and a colloidal solution. When a beam of light is passed through a colloidal solution, the path of the light is visible, while it is invisible in case of a true solution.
Tyndall effect is applied in the manufacture of `H_(2)SO_(4)` , by contact process. The presence of dust particles in the mixture of `SO_(2)-O_(2)`, is detected by Tyndall effect because dust particles in the gas mixture poison the catalyst used in this process.