breaking an object into smaller pieces by using a hammer allowing an iron chain to remain in salt water until it rusts heating a brown substance until it changes into a gray powder reacting vinegar and baking soda to make white foam and a gas
Which is an example of a physical change?

Options:
- breaking an object into smaller pieces by using a hammer
- allowing an iron chain to remain in salt water until it rusts
- heating a brown substance until it changes into a gray powder
- reacting vinegar and baking soda to make white foam and a gas

breaking an object into smaller pieces by using a hammer