Assertion (A): A bell ringing in an evacuated jar cannot be heard.
Reason (R) : Sound waves in a gas are longitudinal

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 but R is true.

Explanation

To solve the question, we need to analyze both the assertion (A) and the reason (R) given in the problem.

### Step 1: Understand the Assertion (A)
The assertion states: "A bell ringing in an evacuated jar cannot be heard."

- When a bell rings, it produces sound waves. However, sound requires a medium (like air, water, or solids) to travel.
- An evacuated jar means that all the air has been removed from the jar, creating a vacuum inside.
- In a vacuum, there are no particles to transmit the sound waves. Therefore, even though the bell is ringing, the sound cannot travel through the vacuum, and thus it cannot be heard.

**Conclusion for Step 1**: The assertion is correct.

### Step 2: Understand the Reason (R)
The reason states: "Sound waves in a gas are longitudinal."

- Sound waves are indeed longitudinal waves, meaning that the particles of the medium (in this case, gas) vibrate back and forth in the same direction as the wave travels.
- This is a characteristic of sound waves, whether they travel through air or any other medium.

**Conclusion for Step 2**: The reason is also correct.

### Step 3: Analyze the Relationship Between A and R
Now we need to determine if the reason (R) correctly explains the assertion (A).

- While both statements are true, the reason does not explain why the sound from the bell cannot be heard in an evacuated jar. The reason describes the nature of sound waves but does not address the absence of a medium in a vacuum.
- Therefore, while both A and R are true, R does not provide the correct explanation for A.

### Final Conclusion
Both the assertion (A) and the reason (R) are true, but the reason is not the correct explanation for the assertion.

Thus, the answer to the question is:
- Option 2: Both A and R are true, but R is not the correct explanation of A.

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