What do these two changes have in common?
snowflakes forming in a cloud
breaking a piece of glass

 - Both are chemical changes.
 - Both are only physical changes.
 - Both are caused by cooling.
 - Both are caused by heating.
Step 1: Think about each change.
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.
Breaking a piece of glass is a physical change. The glass gets broken into pieces. But each piece is still made of the same 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.
A snowflake begins to form when a tiny drop of liquid water in a cloud freezes. This is caused by cooling. But breaking a piece of glass is not.