What do these two changes have in common?
mixing sand and water
cutting your fingernails

 - Both are caused by cooling.
 - Both are chemical changes.
 - Both are only physical changes.
 - Both are caused by heating.
Step 1: Think about each change.
Mixing sand and water is a physical change. Adding water makes the sand wet. But both the sand and water are still made of the same type of matter as before.
Cutting your fingernails is a physical change. Your fingernails are shorter after you cut them. But the pieces are still made of the same type of matter as the uncut fingernails.
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.