Assertion:- Boric acid cannot be titrated with NaOH solution.
Reason:- Cupellation is the process used to remove silver impurity from Pb.
Reason:- This method is used when metal is easily oxidised by air but oxidation of impurity is not possible.

Options

A. If both Assertion `&` Reason are True `&` the Reason is a correct explanation of the Assertion.
B. If both Assertion `&` Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion `&` Reason are False.

Answer

To solve the given assertion-reason question, we will break down the statements and analyze them step by step.

### Step 1: Analyze the Assertion
**Assertion:** Boric acid cannot be titrated with NaOH solution.

- **Explanation:** Boric acid (H₃BO₃) is a weak acid. It does not behave as a typical Bronsted acid, which donates protons (H⁺) in solution. Instead, boric acid acts as a Lewis acid, meaning it accepts electron pairs. When titrated with NaOH (a strong base), boric acid tends to exhibit slight basic characteristics due to its electron-accepting nature. Therefore, it is not suitable to titrate boric acid with NaOH.

**Conclusion for Assertion:** The assertion is **true**.

### Step 2: Analyze the Reason
**Reason:** Cupellation is the process used to remove silver impurity from lead.

- **Explanation:** Cupellation is indeed a metallurgical process used to separate noble metals (like gold and silver) from base metals (like lead). This process involves heating the ore in a controlled environment at high temperatures, allowing the noble metals to be extracted effectively. Therefore, this statement is also **true**.

**Conclusion for Reason:** The reason is **true**.

### Step 3: Determine the Relationship
- The assertion states that boric acid cannot be titrated with NaOH due to its weak acid nature and behavior as a Lewis acid.
- The reason discusses the cupellation process, which is unrelated to the titration of boric acid.

**Conclusion on Relationship:** While both the assertion and reason are true, the reason does not explain the assertion.

### Final Answer
Based on the analysis:
- Both the assertion and reason are true, but the reason is not a correct explanation for the assertion. Therefore, the correct option is that both assertion and reason are true, but the reason is not a correct explanation for the assertion.