What do these two changes have in common?
burning food on a stove
water boiling on a stove

 - Both are caused by heating.
 - Both are chemical changes.
 - Both are only physical changes.
 - Both are caused by cooling.
Step 1: Think about each change.
Food burning on a stove is a chemical change. The type of matter in the food changes. The food turns black and gives off smoke.
Water boiling on the stove is a change of state. So, it is a physical change. The liquid changes into a gas, but a different type of matter is not formed.
Step 2: Look at each answer choice.
Both are only physical changes.
Water boiling is a physical change. But burning food on a stove is not.
Both are chemical changes.
Burning food on a stove is a chemical change. But water boiling is not.
Both are caused by heating.
Both changes are caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.