Question

The colloidal system consisting of a liquid adsorbent in a solid adsorbate is termed as
(A) Aerosol
(B) Emulsion
(C) Foam
(D) Gel

Answer 1

Hint: A colloid is a homogeneous mixture of non-crystalline substance consisting of large molecules of one substance dispersed through a second substance. The colloidal system consisting of a liquid adsorbent in a solid adsorbate is termed as gel.

Complete Step by Step Solution:
By changing the type of adsorbate and adsorbent we can get different types of colloidal systems. Such colloidal systems are as follows:
- The colloidal system consisting of a liquid adsorbent in a solid adsorbate is termed as gel. Here dispersion of liquid takes place in solid substances. Example of gel is cold cream.
- The suspension of liquid or solid particles in gas is called aerosol. The examples of aerosol are fog, mist etc.
- The dispersion of one liquid in another liquid is called emulsion. Here the two liquids must be immiscible. The examples of emulsion are egg yolk, butter.
- The dispersion of gas in solid or liquid is called foam. Examples of foam are soap bubbles and whipped cream.
Thus the correct option is D.

Note: The process of holding gas, liquid or solid molecules on solid is called as adsorption. There are two types of adsorption present. One of these is physical adsorption and another one is chemical adsorption. All the colloids undergoes adsorption.