Question

What kind of colloidal solution is an emulsion?
(A) solid dispersion in liquid
(B) liquid dispersion in liquid
(C) gas dispersed in a liquid
(D) liquid dispersion in solid

Answer 1

Hint: A colloid is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium. The essential difference between a solution and a colloidal solution is that of particle size. Colloidal particles have more surface area per unit mass as a result of their small size.

Complete step by step solution:
Colloids are classified based on the following criteria:
(a) the physical state of the dispersed phase and a dispersed medium
(b) natural of interaction between the dispersion phase and dispersion medium]
(c) type of particles of the dispersed phase
Classification of colloids based on the physical state of the dispersed phase and dispersed medium:
Whether dispersion medium or dispersion phase is solids, liquids, or gases with exists eight types of systems possible:
The examples of the various types of colloids along with their typical names are listed in the table below.

Dispersed phase	Dispersion medium	Type of colloid	Examples
Solid	Solid	Solid sol	Gemstones
Solid	Liquid	Sol	Pains, cell fluids
Solid	Gas	Aerosol	Smoke, dust
Liquid	Solid	Gel	Cheese, butter
Liquid	Liquid	Emulsion	Milk, hair cream
Liquid	Gas	Aerosol	Fog, cloud, dust
Gas	Solid	Solid sol	Foam rubber
Gas	Liquid	Foam	Soap lather

From the above table, an emulsion is a liquid dispersed in a liquid kind of colloidal solution.

So, the correct answer is option B.

Note: A gas mixed with other gas forms a homogeneous mixture and hence the system is not a colloidal system. If the dispersion medium is water in emulsions, it is called aquasol or hydrosol, and if the dispersion medium is alcohol, is called alcohol.