Assertion (A): When common salt is kept open, it absorbs moisture from the air.
Reason (R ): Common salt contains magnesium chloride.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is NOT the correct explanation of A.
C. A is true but R is false.
D. A is false and R is True.

Explanation

To analyze the given statements regarding common salt, we will break down the assertion and the reason step by step.

### Step 1: Understand the Assertion
- **Assertion (A)**: When common salt is kept open, it absorbs moisture from the air.
- **Explanation**: This statement is true. Common salt (sodium chloride, NaCl) can absorb moisture from the air, especially in humid conditions.

**Hint**: Think about how salt behaves in different humidity levels.

### Step 2: Understand the Reason
- **Reason (R)**: Common salt contains magnesium chloride.
- **Explanation**: This statement is misleading. While magnesium chloride (MgCl2) is indeed a deliquescent substance that absorbs moisture, common table salt is primarily sodium chloride (NaCl), not magnesium chloride. However, some types of salt may contain magnesium chloride as an impurity, but it is not a defining component of common salt.

**Hint**: Consider the composition of common salt versus other salts.

### Step 3: Analyze the Relationship between A and R
- The assertion is true, but the reason provided is not accurate in the context of common salt being primarily sodium chloride. Therefore, while both statements may have elements of truth, the reason does not correctly explain the assertion.

**Hint**: Evaluate if the reason logically supports the assertion.

### Conclusion
- **Final Evaluation**: Both statements are not entirely aligned. The assertion is true, but the reason does not correctly explain the assertion specifically for common salt.

**Answer**: The correct option is that the assertion is true, but the reason is false.