Question

Fog is an example of colloidal system of-
(A) Liquid in gas
(B) Gas in liquid
(C) Solid in gas
(D) Gas in solid

Answer 1

Hint: Colloids are mixes in which insoluble particles from one material are microscopically dispersed and suspended into another. The size can vary between 1 and 1000 nanometres (10-9 metres) of the suspended particles in a colloid. The suspended particles of a mixture must not settle down (so that the suspension particles settle at the bottom of a bowl, if left uninterrupted) if the mixture is classified as a colloid.

Complete step by step solution:

Hydrophilic Colloids: these are colloids that love water. The water attracts the colloid particles. They are often referred to as reversible sols. E.g. Agar, gelatin etc.
Hydrophobic Colloids: these are opposed to hydrophilic colloids in nature. Water repels the colloid particles. Often known as permanent sols. Types include gold, clay, etc.
Types based on the dispersed medium-
When the dispersed medium is gaseous:

1. Liquid Aerosol- When the dispersed phase is said to be liquid. For example, fog, mist etc.
2. Solid Aerosol- When the dispersed phase is said to be solid. For example, smoke etc

When the dispersed medium is solid:

1. Gel- When the dispersed phase is said to be liquid. For example, gelatin etc.
2. Solid Sol- When the dispersed phase is said to be solid. For example, cranberry glass.
3. Solid Foam- When the dispersed phase is said to be gas. For example, Styrofoam etc.

When the dispersed medium is liquid:

1. Foam- When the dispersed phase is said to be gas. For example, whipped cream etc.
2. Emulsions- When the dispersed phase is said to be liquid. For example, mayonnaise etc.
3. Sol- When the dispersed phase is said to be solid. For example, blood etc.
   Hence, it is clear that Fog is the part of a colloidal system in which liquid is said to be dispersed in gas.

Thus, it is clear that option A is the correct option.

Note: The Tyndall Effect, a phenomenon in which light beam incidents on colloids are scattered due to interactions between light and colloidal particles, is known to display by the colloidal solutions.