evaporation of water grinding of rock melting of ice rusting of iron
I gave my students this multiple choice question: Louis was investigating physical and chemical changes in matter. Which of these changes that Louis found involves a chemical change in matter?

Only one answer is correct among these 4 choices:
- evaporation of water
- grinding of rock
- melting of ice
- rusting of iron

Could you tell me which one is correct?

rusting of iron