Which of the following will not cause coagulation of a colloid?

Addition of peptizing agent

The correct answer is option 2. Addition of peptizing agent.

Coagulation of a colloid refers to the process where the dispersed particles come together and form larger aggregates, leading to the precipitation or settling of the colloidal particles. To prevent coagulation, various methods can be employed. Let's analyze each option:

1. Electrophoresis:  This involves applying an electric field to the colloid, causing the charged colloidal particles to migrate toward the oppositely charged electrode. This can prevent coagulation by maintaining a stable dispersion.

2. Addition of Peptizing Agent: A peptizing agent is a substance that helps in preventing coagulation and keeps the colloidal particles dispersed. Therefore, adding a peptizing agent would not cause coagulation; instead, it stabilizes the colloid.

3. Boiling: Boiling can lead to coagulation by reducing the repulsion between colloidal particles. When a colloid is heated, the thermal motion of particles increases, and coagulation may occur.

4. Persistent Dialysis: Dialysis involves the separation of colloidal particles from electrolytes by allowing them to pass through a semipermeable membrane. Persistent dialysis helps in preventing coagulation by removing any ions or impurities that might cause destabilization.

Based on the options provided, the method that will not cause coagulation is: (2) Addition of peptizing agent

Adding a peptizing agent helps in stabilizing the colloid and preventing coagulation.