Reversible binding of cations, a property possessed by clay particle, is known as

Options

A. Retentive capacity
B. Cation exchange
C. Adsorption
D. Chelation

Answer

To solve the question regarding the reversible binding of cations, a property possessed by clay particles, we will analyze the options provided and identify the correct term that describes this phenomenon.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the term that describes the reversible binding of cations by clay particles. This is a specific property related to how clay interacts with positively charged ions (cations).

2. **Analyzing the Options**:
- **Option 1: Retentive capacity**: This term generally refers to the ability to hold onto something. While clay does have a retentive capacity, this term does not specifically describe the reversible nature of cation binding.
- **Option 2: Cation exchange**: This term refers to the process where one cation bound to a surface can be replaced by another cation. This process is reversible, meaning that cations can be exchanged back and forth, which aligns with the question's description.
- **Option 3: Adsorption**: This term refers to the process where particles adhere to a surface. However, it does not specifically imply reversibility or the exchange of cations.
- **Option 4: Chelation**: This term refers to the formation of complex structures between metal ions and organic molecules. It does not pertain to the reversible binding of cations in the context of clay.

3. **Identifying the Correct Answer**: Based on the analysis, the term that best describes the reversible binding of cations by clay particles is **cation exchange**. This is because cation exchange specifically involves the ability of clay to hold and swap cations in a reversible manner.

4. **Conclusion**: The correct answer to the question is **cation exchange**.