7TH GRADE

Physical changes are usually reversible and do not change the substance's identity.

Rust forming on a piece of iron is an example of which of the following:

Chemical changes are reversible and do not change the substance's identity.

Burning paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone.

Which of the following is the best description of the results of a chemical reaction?

Freezing water is an example of a physical change because the process can be undone.

Cutting paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone.