A : If dipole moment of water molecules were zero, then microwave cooking would not be possible.
R : In a microwave oven the water molecules vibrate due to oscillating electric field in microwave and heat the food.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the 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 Reason are false statements, then mark (4).

Answer

To solve the problem, we need to analyze the two statements given:

**Statement A:** If the dipole moment of water molecules were zero, then microwave cooking would not be possible.
**Statement R:** In a microwave oven, the water molecules vibrate due to the oscillating electric field in the microwave and heat the food.

### Step-by-Step Solution:

1. **Understanding the Dipole Moment:**
- The dipole moment is a measure of the separation of positive and negative charges in a molecule. Water (H₂O) has a significant dipole moment because of its bent shape and the difference in electronegativity between hydrogen and oxygen.

2. **Analyzing Statement A:**
- If the dipole moment of water molecules were zero, it implies that water would behave like a non-polar molecule. Non-polar molecules do not interact significantly with electric fields.
- Microwaves work by creating an oscillating electric field that interacts with polar molecules. This interaction causes polar molecules like water to rotate and vibrate, generating heat.
- Therefore, if the dipole moment were zero, water molecules would not respond to the microwave's electric field, making microwave cooking impossible.
- **Conclusion:** Statement A is correct.

3. **Analyzing Statement R:**
- Statement R explains the mechanism of how microwave cooking works. The oscillating electric field in the microwave causes polar water molecules to vibrate.
- This vibration leads to an increase in thermal energy, which heats the food.
- **Conclusion:** Statement R is also correct.

4. **Checking if R is the Correct Explanation of A:**
- Statement R provides a clear explanation of why Statement A is true. It describes the role of the dipole moment in the functioning of microwave ovens.
- Since the dipole moment allows water molecules to respond to the electric field, it directly supports the claim made in Statement A.
- **Conclusion:** R is indeed the correct explanation of A.

### Final Conclusion:
Both statements A and R are correct, and R is the correct explanation of A.

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