Which of the following colloids is most stable?

Starch solution

The correct answer is option 1. Starch solution.

Stability depends on various factors, and different colloids can exhibit stability under different conditions. However, here's a breakdown to help you analyze their relative stability:

1. Starch solution: This is a lyophilic colloid (solvent-loving) where starch molecules are dispersed in water. Lyophilic colloids tend to be relatively stable due to the affinity between the dispersed particles and the medium. However, factors like high temperature or enzymatic breakdown can affect their stability.

2. Blood: Blood is a complex suspension containing various components like red blood cells, white blood cells, platelets, and plasma. The stability of blood depends on factors like pH, electrolyte balance, and proteins present in the plasma. Generally, healthy blood exhibits good stability within the body.

3. Sulphur solution: This is a lyophobic colloid (solvent-hating) where sulphur particles are dispersed in water. Lyophobic colloids are generally less stable than lyophilic ones. Sulphur particles might have a tendency to aggregate or precipitate over time, especially if the solution is concentrated or not properly prepared.

4. Silver solution: This can also be categorized as a lyophobic colloid where silver particles are dispersed in a medium. Similar to the sulphur solution, silver sol tends to be less stable and can aggregate or precipitate if not prepared or stored properly.

Factors Affecting Stability:

Here are some key factors that influence the stability of colloids:

Nature of dispersed phase and medium: Lyophilic colloids tend to be more stable due to the affinity between particles and the medium.

Particle size: Smaller particles generally exhibit greater stability due to a larger surface area to volume ratio.

Charge on particles: Colloids with charged particles can repel each other, preventing aggregation and enhancing stability.

Presence of stabilizing agents: Emulsifiers and surfactants can create a barrier around dispersed droplets, improving stability.

Conclusion:

While it's challenging to pinpoint the absolute most stable colloid, based on general trends, starch solution (a lyophilic colloid) might be considered relatively more stable due to the affinity between starch molecules and water. However, stability can be influenced by various factors, and the answer might change depending on the specific conditions.