What do these two changes have in common?
filtering air to remove dust and pollen
pouring milk on oatmeal

 - Both are caused by heating.
 - Both are caused by cooling.
 - Both are only physical changes.
 - Both are chemical changes.
Step 1: Think about each change.
Filtering air to remove dust and pollen is a physical change. The air flows through the filter, and the pollen and dust stay behind. This separates the mixture of air, pollen, and dust. But separating a mixture does not form a different type of matter.
Pouring milk on oatmeal is a physical change. The oatmeal and milk form a creamy mixture. But making this mixture does not form a different type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.