When you burn wood into ash or burn a marshmallow to become brown and crispy, it is impossible to undo.  this change is known as what?
physical change
carbon change
compounding change
chemical change
Yummy! S’mores are on the way! Did you ever toast marshmallows over a campfire? The sweet treats singe on the outside and melt on the inside. Both the fire and the toasted marshmallows are evidence of chemical changes. In the process of burning, the wood changes to ashes and gases, and the outside of the marshmallow turns brown and crispy. Neither the wood nor the marshmallows can change back to their original form. That’s because burning is a chemical change and chemical changes are often impossible to undo. In this unit, you’ll learn about many types of chemical changes, including how they occur and why you can’t live without them.