Which actions are evidence that a chemical reaction has occurred? Check all that apply.

What must be done to be certain that a chemical change has taken place?

When a substance changes states (melts, evaporates, etc.) it is often what type of change?

Which of the following is a clue that a chemical change has taken place?

The oxidation of haircolor is an example of a _____.

Which statement best describes evidence that a chemical reaction occurs as a cake bakes?

Which of the following is an example that includes evidence of a chemical change?