Question

Sticking of one substance at the surface of another is called
A. Absorption
B. Chemisorption
C. Adsorption
D. Desorption

Answer 1

Hint: To answer this question we have to know about all the processes. Absorption is a phenomenon where a gas, liquid or solid is absorbed by another substance. Two types of absorption are present. One of this is physical absorption and another one is chemical absorption.

Complete Step by Step Answer:
- Sticking one substance on the surface of another substance by some intermolecular or chemical force is called adsorption.
- In the process of adsorption the species which get adsorbed is called adsorbate and the adsorption medium is called as adsorbent.
- The process where some atom, molecule or ions enter the bulk of a system is defined as absorption.
- The reverse process of adsorption is termed as desorption.
- Chemical adsorption takes place between the adsorbate and adsorbent due to chemical or ionic bonding. It is dependent on temperature and is highly affected by any change in temperature.
Thus the correct option is C.

Additional Information: 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.

Note: As the amount of adsorbate in the solution increases, interaction between the adsorbate with adsorbent also increases and this leads to the increase in the extent of adsorption.By changing the type of adsorbate and adsorbent in the process of adsorption we can get different types of systems which are called as colloids. Some colloids are gel, foam etc.