What do these two changes have in common?
a piece of pear turning brown
baking cookies

 - Both are chemical changes.
 - Both are caused by cooling.
 - Both are only physical changes.
 - Both are caused by heating.
Step 1: Think about each change.
A piece of a pear turning brown is a chemical change. The substances in the pear react with oxygen in the air and turn into a different type of matter.
If you scrape off the brown part of the pear, the inside will still be white. The inside hasn't touched the air. So the chemical change hasn't happened to that part of the pear.
Baking cookies is a chemical change. The type of matter in the cookie dough changes when it is baked. The cookie dough turns into cookies!
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.
Baking is caused by heating. But a piece of pear turning brown is not.
Both are caused by cooling.
Neither change is caused by cooling.