Two substances have different reactions to light. Two substances have different temperatures. Two substances have different volumes. Two substances have different shapes.
I gave my students this multiple choice question: What would be the best evidence that two substances are made of different types of matter?

Only one answer is correct among these 4 choices:
- Two substances have different reactions to light.
- Two substances have different temperatures.
- Two substances have different volumes.
- Two substances have different shapes.

Could you tell me which one is correct?

Two substances have different reactions to light.