Answer the question on the basis of passage given below:

Adsorption is the phenomenon of attracting and retaining the molecules of a substance on the surface of a solid resulting into a higher concentration on the surface than in the bulk. The variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature is expressed as isotherm. A catalyst is a substance, when adsorbed enhances the rate of a chemical reaction without itself getting used up in the reaction. Depending on the type of the particles of the dispersed phase, colloids are classified as multimolecular, macromolecular and associated colloids and soap is such an example of associated colloids. Colloids show various properties such as Tyndall effect, colour, Brownian movement and charge development. There are positively charged sols and negatively charged sols. Due to this, electrophoresis and electroosmosis are shown by colloids.

The charge on the sol particles cannot be produced by-

presence of excess quantity of the dispersion medium.

The correct answer is Option (4) → presence of excess quantity of the dispersion medium.

The correct answer is presence of excess quantity of the dispersion medium.

Let us look at the given options:

1. Electron Capture by Sol Particles During Electro-Dispersion of Metals:

In electro-dispersion, metal particles can capture electrons, leading to the formation of charged sol particles. This contributes to the charge on the sol.

2. Preferential Adsorption of Ions from Solution:

This process involves ions from the surrounding solution being adsorbed onto the surface of the sol particles, which can result in a net charge on the sol.

3. Formation of Electrical Double Layer:

When sol particles are dispersed in a medium, they can develop an electrical double layer due to the adsorption of ions. This is a fundamental mechanism for charge stabilization in colloidal systems.

4. Presence of Excess Quantity of the Dispersion Medium:

The excess dispersion medium does not directly contribute to the charge on the sol particles. Instead, it serves to dilute the concentration of sol particles and does not influence their inherent charge properties.

Conclusion:

Thus, the charge on sol particles cannot be produced by the presence of an excess quantity of the dispersion medium