Q: What type of change has occurred when a copper penny changes color?


Read this paragraph and choose the correct option from the provided answers:

Some of these pennies are shiny and copper colored. That’s how pennies look when they are new. The older pennies are dull and brown. Copper at the surface of these pennies has combined with air to become a different substance with different properties. The change in color shows that a chemical change has occurred.

 Choices:

- contamination change

- carbon change

- reactive change

- chemical change


A:
chemical change