Put a heart on the blank before the number if the following situation demonstrate sound energy transformation and cross if not.

1. pressing a doorbell
2. ironing the clothes
3. roasting a duck leg
4. plucking on a guitar
5. crumpling of paper
6. sitting on a bench
7. closing a car door
8. boiling of water
9. popping of balloons
10. turning on the radio ​