Question

There are two boxes A & B. Cell phones are kept in both the boxes, all air is sucked from box A which is then closed. While box B is simply closed without sucking air from it. A call is made simultaneously on both the phones, but sound comes only from box B. This is because:

Statement 1: In box B there are air particles to vibrate but in box A there is a vacuum.
Statement 2: Sound needs a medium for propagation.

• A. Statement 1 is true and statement 2 is the correct explanation of statement 1
• B. Statement 1 is true but statement 2 is not the correct explanation of statement 1
• C. Statement 1 is true but statement 2 is false
• D. Statement 1 is false but statement 2 is true

Answer 1

The correct option is A

Statement 1 is true and statement 2 is the correct explanation of statement 1

In box A, there are no air particles that can vibrate, so sound does not propagate in box A and no sound is heard. But in box B there are air particles that can vibrate and hence sound propagates.