What do these two changes have in common?
melting wax
snowflakes forming in a cloud

 - 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.
Melting wax is a change of state. So, it is a physical change. The wax changes from solid to liquid. But it is still made of the same type of matter.
Snowflakes forming in a cloud is a change of state. So, it is a physical change. Liquid water freezes and becomes solid, but it is still made of water. A different type of matter is not formed.
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.
Wax melting is caused by heating. But snowflakes forming in a cloud is not.
Both are caused by cooling.
A snowflake begins to form when a tiny drop of liquid water in a cloud freezes. This is caused by cooling. But melting wax is not.