Assertion: `NaCI` when exposed in air it becomes wet.
Reason: `NaCI` contains hygroscopic impurities like `CaCI_(2), MgCI_(2)` etc.

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

Explanation

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

### Step 1: Understand the Assertion
The assertion states that "NaCl when exposed in air it becomes wet." This means that sodium chloride (common salt) absorbs moisture from the air when left out.

**Hint:** Consider what happens to common salt when it is left out in a humid environment.

### Step 2: Understand the Reason
The reason given is that "NaCl contains hygroscopic impurities like CaCl₂ and MgCl₂." Hygroscopic substances are those that can absorb moisture from the air.

**Hint:** Think about the properties of hygroscopic substances and how they interact with moisture.

### Step 3: Connect the Assertion and Reason
Since the reason explains that NaCl contains hygroscopic impurities (CaCl₂ and MgCl₂), which have a strong affinity for water, it logically follows that these impurities would cause NaCl to absorb moisture when exposed to air.

**Hint:** Reflect on how the presence of these impurities directly leads to the assertion being true.

### Step 4: Conclusion
Both the assertion and the reason are correct, and the reason provides a correct explanation for the assertion. Therefore, the answer to the question is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

**Final Answer:** The answer is option (a) - both the assertion and reason are correct, and the reason is the correct explanation of the assertion.

### Summary of Steps:
1. Analyze the assertion about NaCl becoming wet in air.
2. Analyze the reason regarding hygroscopic impurities.
3. Connect the assertion and reason logically.
4. Conclude that both are true and the reason explains the assertion.