ANSWER:

1. A empty bottle can produces a lower pitch

2. A empty bottle produces a lower pitch because there's a lot's of air

3. If you knock the spoon and fork into the edge of the table to produced "GONG" sounds

4. It can be produced by vibration

5.glass creates sound when you rub your finger around its rim or strike it with an object.

6.They have no specialized structure to perceive sound like we do, but a new study has found that plants

7. When bamboo is heated, the air in the sealed hollow internode chambers will expand and cause an explosive bam-boom sound.