How do you know? Explain your answer.

Explanation:

You know this because its like an experiment. If you burn paper you can not make that paper again its just ash. With physical: If you microwave butter its melted butter but still butter. That's the interesting thing about this whole experiment, you can microwave something and it can melt but it's still what it was in the beginning. With chemical change: If you freeze ice and then it melts and its not at its original state then it can never go back to its original state because you froze it and melted it now its just water.  

Hope I helped!