What do these two changes have in common?
a copper statue turning green
compost rotting

 - Both are caused by heating.
 - Both are caused by cooling.
 - Both are chemical changes.
 - Both are only physical changes.
Step 1: Think about each change.
A copper statue turning green is a chemical change. The copper reacts with oxygen in the air. This reaction forms a different type of matter called copper oxide. The copper oxide is green.
Compost forms from the remains of plants and animals, such as vegetable scraps and egg shells. Compost rotting is a chemical change. As the compost rots, it breaks down and turns into a different type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.