Question

The dispersion of liquid or solid in air is called:
A. Aerosol
B. Foam
C. Gels
D. Sol

Answer 1

Hint: Colloidal solutions are classified on the basis of their physical state of dispersed phase and dispersion medium. If the dispersion medium is air then the sol is called aerosol. They can be natural or anthropogenic.

Complete step-by-step answer:
A colloid is a mixture of particles of nanometers in diameter, also called colloidal dispersions because the substances remain dispersed and do not settle at bottom. They may either dissolve macromolecules or may represent a separate phase, such as powders, emulsions, aerosols, etc.
In colloids, one substance is evenly dispersed in another substance. The substance being dispersed is called dispersed phase while the substance in which it is dispersed is the dispersion medium. The size of colloidal particles is in the range of 1nm to \[1\mu m\]. Colloids are prepared by mechanical dispersion, Bredig’s Arc method, peptization, etc.
Colloids are majorly classified as:
- Sol is a colloidal suspension with solid particles in a liquid which is a dispersion medium.
- Foam is formed when gas particles get trapped in either solid or liquid.
- Emulsion is between two liquids i.e. dispersion phase and dispersion medium both are liquid.
- Aerosols have small particles of liquid or solid dispersed in a gas or air which is the dispersion medium here.
- Sol is a colloidal system of solid dispersed in liquid medium.

Hence, the correct option is (A).

Note: The interchange of dispersion phase and dispersion medium changes the colloidal system. For example, in the case of the colloidal system of liquid dispersed in a solid dispersion medium, it is referred to as gel.