Activity 4 Directions: Put check on the space provided if the materials undergo change with the presence of oxygen and X if It undergoes a change due to lack of oxygen.
1. diced onion
2. burnt paper
3. souring of milk
4 grinding coffee
5. rusted iron
6. spoiled food
7 pounding of chalk
8. ironing of clothes
9. digesting of food
10. tearing of paper