put / 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​