Assertion : When KI solution is added to `AgNO_(3)` solution, negatively charged sol results .
Reason : Negative charge of sol is due to preferential adsorption of iodide ions from the dispersion medium.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. if both assertion and reason are false

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understanding the Assertion
The assertion states that when KI (potassium iodide) solution is added to AgNO₃ (silver nitrate) solution, a negatively charged sol is formed.

- When KI is added to AgNO₃, a double displacement reaction occurs, leading to the formation of silver iodide (AgI) precipitate:
\[ \text{AgNO}_3 + \text{KI} \rightarrow \text{AgI} \downarrow + \text{KNO}_3 \]
- In this reaction, AgI forms as a solid precipitate, and the remaining ions in the solution are K⁺ and NO₃⁻.

### Step 2: Analyzing the Charge of the Sol
The assertion claims that the sol formed is negatively charged. However, when AgI precipitates, it is the Ag⁺ ions that are preferentially adsorbed onto the surface of the precipitate. This results in a positively charged sol, not a negatively charged one.

### Step 3: Understanding the Reason
The reason states that the negative charge of the sol is due to the preferential adsorption of iodide ions (I⁻) from the dispersion medium.

- This statement is incorrect because, as established, it is the Ag⁺ ions that are adsorbed onto the surface of the AgI precipitate, leading to a positive charge rather than a negative charge.

### Conclusion
Both the assertion and the reason are incorrect. Therefore, the correct answer is that both statements are false.

### Final Answer
Both the assertion and the reason are false.

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