What do these two changes have in common?
mixing sand and gravel
adding dish soap to water in a sink

 - 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.
Mixing sand and gravel is a physical change. Together, the sand and gravel make a mixture. But making this mixture does not form a different type of matter.
Adding dish soap to water in a sink is a physical change. Bubbles may appear if air gets trapped in the soapy water, but a different type of matter does not form.
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.