The combination of two layers of opposite charges aroung the colloidal particle is called Helmholtz electrical double layer. The potential difference between the fixed layer and the diffused layer of opposite charge is called

Options

A. electrode potential
B. zeta potential
C. adsorption potential
D. diffused potential

Explanation

To solve the question regarding the potential difference between the fixed layer and the diffused layer of opposite charge in a colloidal particle, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Helmholtz Electrical Double Layer**:
- The Helmholtz electrical double layer consists of two layers of charge surrounding a colloidal particle. One layer is fixed (the Stern layer) and the other is diffused (the diffuse layer).

2. **Identifying the Charges**:
- In our example, we consider a negatively charged colloidal particle (the sol). This particle will attract positively charged ions from the surrounding medium, forming a positively charged layer around it.

3. **Defining the Layers**:
- The fixed layer (Stern layer) consists of the positive ions that are closely associated with the negatively charged colloidal particle.
- The diffused layer consists of additional positive ions that are more loosely associated and are distributed in the surrounding medium.

4. **Potential Difference**:
- The potential difference that exists between the fixed layer (where the positive ions are closely bound) and the diffuse layer (where the positive ions are more dispersed) is significant in characterizing the stability and behavior of colloidal systems.

5. **Naming the Potential Difference**:
- This potential difference is known as the **zeta potential** (ζ potential). It is a measure of the magnitude of the electrostatic repulsion or attraction between particles in a colloidal system.

### Final Answer:
The potential difference between the fixed layer and the diffused layer of opposite charge is called **zeta potential**.