In a colloidal state the particle size of the dispersed phase range between \(10^3\) to \(10^6\) pm and colloidal sol is heterogenous in nature. Based on the nature of interaction between the dispersed phase and dispersion medium colloidal sol are classified as lyophilic and lyophobic. Stability of sol is due to presence of charge on the sol particles and the neutralization of the same is known as coagulation or precipitation.

Based on this answer the following:

Lyophillic sols are more stable than lyophobic sols because

The colloidal particles are solvated

The correct answer is option 3. The colloidal particles are solvated.

Lyophilic sols are colloidal solutions where the dispersed phase (colloidal particles) has an affinity for the dispersion medium (solvent). In contrast, lyophobic sols are colloidal solutions where the dispersed phase has little or no affinity for the dispersion medium.

The stability of lyophilic sols compared to lyophobic sols arises due to the interactions between the dispersed phase and the dispersion medium.

Let us look at why ption 3 is correct:

In lyophilic sols, the colloidal particles are solvated, meaning they are surrounded by a layer of solvent molecules. This solvation occurs because the dispersed phase has an affinity for the dispersion medium. The solvent molecules form a protective layer around the colloidal particles, preventing their aggregation and providing stability to the colloid. This solvation layer acts as a barrier, preventing the colloidal particles from coming into close contact and coalescing.

In lyophobic sols, on the other hand, the dispersed phase does not have a strong affinity for the dispersion medium. Therefore, there is no solvation of the colloidal particles, making them more prone to aggregation and instability.

Options 1, 2, and 4 are not accurate explanations for the stability of lyophilic sols. Positive charge on colloidal particles (Option 1) or the absence of charge (Option 2) do not necessarily contribute to the stability of lyophilic sols. While the addition of a small amount of electrolyte (Option 4) can stabilize colloidal solutions, it is not a characteristic feature specific to lyophilic sols.