Assertion : Longitudinal waves are also known as pressure waves.
Reason : Because propagation of these waves in air causes changes in pressure and volume of the air.

Options

A. If both assertion and reason are correct and reason is a correct explanation of the assertion.
B. If both assertion and reason are correct but reason is not the correct explanation of assertion.
C. If assertion is correct but reason is incorrect
D. If assertion is incorrect but reason is correct.

Answer

**Step-by-Step Solution:**

1. **Understanding Longitudinal Waves:**
- Longitudinal waves are waves in which the particle displacement is parallel to the direction of wave propagation. A common example of longitudinal waves is sound waves.

2. **Assertion Analysis:**
- The assertion states that "Longitudinal waves are also known as pressure waves." This is true because in longitudinal waves, areas of compression and rarefaction occur, which directly relate to changes in pressure.

3. **Reason Analysis:**
- The reason given is "Because propagation of these waves in air causes changes in pressure and volume of the air." This is also true. As sound waves travel through air, they create regions where air molecules are compressed (increased pressure) and regions where they are spread apart (decreased pressure).

4. **Linking Assertion and Reason:**
- The reason explains why longitudinal waves are referred to as pressure waves. The changes in pressure and volume during the wave's propagation are fundamental characteristics of how these waves behave in a medium like air.

5. **Conclusion:**
- Since both the assertion and the reason are correct, and the reason correctly explains the assertion, we conclude that both the assertion and reason are true, and the reason is the correct explanation for the assertion.

**Final Answer:**
- Both assertion and reason are correct, and the reason is the correct explanation of the assertion.

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