A : Agl changes to nagatively charged colloidal solution in presence of Kl.
R : It is due to adsorption of `l^(-)` on Agl .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, mark (1)
B. If both Assertion & Reason are true but reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Resson are false statements , then mark (4)

Answer

To solve the question, we will analyze the statements A and R regarding the behavior of AgI in the presence of KI.

### Step-by-Step Solution:

1. **Understanding the Components**:
- AgI (Silver Iodide) is a sparingly soluble salt that can form a colloidal solution.
- KI (Potassium Iodide) dissociates in solution to give K⁺ and I⁻ ions.

2. **Formation of Colloidal Solution**:
- When KI is added to a solution containing AgI, the I⁻ ions from KI are in excess and can interact with AgI.
- This leads to the preferential adsorption of I⁻ ions onto the surface of AgI particles.

3. **Charge Development**:
- The adsorption of negatively charged I⁻ ions on the AgI particles results in the development of a net negative charge on these particles.
- The negatively charged colloidal particles will repel each other, preventing them from aggregating and thus stabilizing the colloidal solution.

4. **Peptidization Process**:
- The process of breaking down larger AgI particles into smaller colloidal particles due to the repulsion caused by the negative charge is known as peptidization.
- The size of these colloidal particles falls within the range of 1 nm to 1000 nm, which is characteristic of colloidal systems.

5. **Conclusion**:
- Therefore, the statement A is true: AgI changes to a negatively charged colloidal solution in the presence of KI.
- The statement R is also true: This change is due to the adsorption of I⁻ ions on AgI.

### Final Answer:
Both statements A and R are correct. A: AgI changes to a negatively charged colloidal solution in the presence of KI. R: It is due to the adsorption of I⁻ on AgI.

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