Which of the following is an example of liquid gas aerosol?

Fog

The correct answer is Option (3) → Fog.

Let us go through each of the given options and explain why fog is the correct example of a liquid-gas aerosol, while the others are not.

An aerosol is a colloidal system where tiny particles or droplets of one substance (solid or liquid) are dispersed in a gas. Specifically, a liquid-gas aerosol consists of liquid droplets dispersed in a gaseous medium.

Explanation of the Options:

1. Froth:

Froth is a colloid, but not an aerosol.  It is a gas-liquid system where gas bubbles are dispersed in a liquid. 

Example: When you shake soap water or when beer forms a head of froth, gas (air) is trapped in the liquid, forming bubbles.

Froth ≠ Aerosol because in froth, the dispersed phase is gas, not liquid.

2. Paints:

Paints are usually a solid-liquid colloid. In paints, solid particles (pigments) are dispersed in a liquid solvent or binder.

Example: In water-based or oil-based paints, tiny pigment particles are suspended in a liquid, which evaporates or dries to form a solid coating.

Paints ≠ Aerosol because paints involve solid particles dispersed in liquid, not liquid droplets dispersed in gas.

3. Fog (Correct Answer):

Fog is an example of a *iquid-gas aerosol. It consists of tiny droplets of liquid water dispersed in the air, which is a gas. The small water droplets remain suspended in the air, giving fog its characteristic misty appearance.

Example: Fog forms when moist air cools and water vapor condenses into tiny liquid droplets, which are suspended in the surrounding air.

Since fog involves liquid droplets (water) dispersed in gas (air), it is an example of a liquid-gas aerosol.

4. Hair Cream:

Hair cream is an example of an emulsion, which is a liquid-liquid colloid. It consists of tiny droplets of one liquid (like oil) dispersed in another liquid (like water). The two liquids are typically immiscible.

Example: In hair cream or lotions, oil droplets are emulsified in water to form a smooth cream.

Hair Cream ≠ Aerosol because it involves two liquids (oil and water), not a liquid dispersed in a gas.

Conclusion:

Fog is the correct example of a liquid-gas aerosol because it involves the dispersion of tiny water droplets (liquid) in air (gas).