The Statue of Liberty is made out of copper and was once shiny and copper-colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material.

Question

What has occurred?

an endothermic reaction
an energy formation
a chemical reaction
a precipitate formation

Answer 1

The process you are describing, where copper undergoes oxidation and changes its appearance and composition, is known as a chemical reaction. Specifically, the copper reacts with elements in the environment, such as oxygen and sulfur, resulting in the formation of copper oxides and other compounds that give the statue its green patina.