Factors affecting the speed of sound are :

1. temperature
2. density
3. pressure
4. only (a) and (b)

The speed of light in air is:

1. 3 x 10⁸ m s^-1
2. 330 m s^-1
3. 5100 m s^-1
4. 3 x 10¹⁰ m s^-1

Complete the following sentence —

Sound is produced by a ………. body.

There is no atmosphere on moon. Can you hear each other on the moon’s surface?