Fog is a colloid in which

Analysis of the Question

The question asks for the classification of fog as a colloidal system. In chemistry, a colloid is a mixture where one substance of microscopically dispersed insoluble particles is suspended throughout another substance. To solve this, we need to identify the dispersed phase (the substance being spread) and the dispersion medium (the substance in which it is spread).

Explanation of the Concept

Colloids are classified based on the physical state of the dispersed phase and the dispersion medium. Here is a quick breakdown of common types:

• Aerosol: Liquid or solid particles dispersed in a gas.
• Foam: Gas particles dispersed in a liquid.
• Emulsion: Liquid particles dispersed in a liquid.
• Sol: Solid particles dispersed in a liquid.

In the case of fog, it consists of tiny droplets of water (which is a liquid) suspended in the air (which is a gas). Therefore, fog is a type of aerosol.

Step-by-Step Solution

1. Identify the components of fog: Fog is essentially water vapor that has condensed into tiny liquid water droplets suspended in the atmosphere.
2. Determine the Dispersed Phase: The water droplets are the substance being dispersed. Since they are water, the phase is liquid.
3. Determine the Dispersion Medium: The droplets are suspended in the air. Air is a mixture of gases, so the medium is gas.
4. Match with the definition: A colloid with a liquid dispersed in a gas is classified as a liquid aerosol.

Looking at the options:

• Option A: Liquid particles dispersed in a gas medium (Matches our analysis).
• Option B: Gas particles dispersed in a liquid medium (This describes foam).
• Option C: Solid particles dispersed in a gas medium (This describes smoke).
• Option D: Gas particles dispersed in a solid medium (This describes solid foam, like pumice stone).

Conclusion

Fog is formed when liquid water droplets are dispersed in the air (gas).

Exam Tip

To remember these easily, use this mnemonic:

• Fog/Mist: Liquid in Gas (Think: "Liquid droplets floating in the air").
• Smoke: Solid in Gas (Think: "Solid ash/soot floating in the air").
• Foam: Gas in Liquid (Think: "Gas bubbles trapped in soap water").