What do these two changes have in common?
a piece of pear turning brown
salt and vinegar removing tarnish from a penny

 - Both are only physical changes.
 - Both are caused by heating.
 - Both are caused by cooling.
 - Both are chemical changes.
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.
Salt and vinegar removing tarnish from a penny is a chemical change. The salt and vinegar change the tarnish into a different type of matter that can be easily wiped away. This makes the penny look shiny again.
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.