What do these two changes have in common?
compost rotting
burning a piece of wood

 - Both are caused by heating.
 - Both are chemical changes.
 - Both are caused by cooling.
 - Both are only physical changes.
Step 1: Think about each change.
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.
Burning a piece of wood is a chemical change. When the wood burns, the type of matter in it changes. The wood turns black and gives off smoke.
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.
Burning is caused by heating. But compost rotting is not.
Both are caused by cooling.
Neither change is caused by cooling.