What do these two changes have in common?
cellular respiration
chemicals in a battery reacting to power a flashlight

 - Both are caused by heating.
 - Both are only physical changes.
 - Both are chemical changes.
 - Both are caused by cooling.
Step 1: Think about each change.
Cellular respiration is a chemical change. Cells use oxygen to break down sugar. Breaking the chemical bonds in sugar molecules releases energy that a cell can use.
The atoms from the broken molecules then combine to form different molecules such as carbon dioxide and water. These molecules are different types of matter than sugar and oxygen.
Chemicals in a battery reacting to power a flashlight is a chemical change. When the flashlight is turned on, the chemicals in the battery react with each other to form new chemicals. This creates electricity, which powers the lightbulb.
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.