Match List I with List II.

Choose the correct answer from the options given below:

(A)-(II), (B)-(III), (C)-(IV), (D)-(I)

The correct answer is option 2. (A)-(II), (B)-(III), (C)-(IV), (D)-(I).

In colloidal chemistry, different types of colloids are classified based on the dispersion medium and the dispersed phase. Here's an explanation of each of the matches:

(A) Solid in liquid - (II) Sol:
When solid particles are dispersed in a liquid medium, it forms a colloidal system known as a sol. In a sol, the solid particles are dispersed throughout the liquid and do not settle down due to gravity. Examples of sols include milk of magnesia and blood.

(B) Liquid in solid - (III) Gel:
When liquid is dispersed in a solid medium, it forms a colloidal system called a gel. Gels have a network structure with the liquid dispersed throughout the solid matrix. They exhibit properties of both solids and liquids. Examples of gels include gelatin and agar.

(C) Liquid in liquid - (IV) Emulsion:
When liquid droplets are dispersed in another liquid medium, it forms a colloidal system known as an emulsion. Emulsions are generally thermodynamically unstable and tend to separate over time into two distinct phases. However, stability can be achieved through the addition of emulsifiers. Examples of emulsions include milk and mayonnaise.

(D) Gas in liquid - (I) Foam:
When gas bubbles are dispersed in a liquid medium, it forms a colloidal system called a foam. Foams are characterized by the presence of gas bubbles surrounded by a liquid film. They exhibit unique properties such as low density and high surface area. Examples of foams include whipped cream and shaving foam.

Each of these colloidal systems plays important roles in various applications, ranging from food and pharmaceutical industries to cosmetics and materials science. Understanding their properties and behavior is crucial for designing and optimizing processes involving colloidal dispersions.