Answer:
1. When an object vibrates, it causes movement. This movement is called sound waves and they can travel through water, wood and air.
2. Whales uses sound to communicate underwater. The main types of sounds are whistles, pulsed calls, and clicks.
3. If a huge explosion occurs on a planet in the solar system it will not be heard on earth because for the sound to pass through it will need a vacuum and the solar system does not have these vacuum making it impossible to hear the sound of explosions taking place on other planets.