What do these two changes have in common?
mixing lettuce and salad dressing
ice crystals forming on a window

 - Both are only physical changes.
 - Both are caused by cooling.
 - Both are caused by heating.
 - Both are chemical changes.
Step 1: Think about each change.
Mixing lettuce and salad dressing is a physical change. Together, the salad and dressing make a mixture. But making this mixture does not form a different type of matter.
Ice crystals forming on a window is a change of state. So, it is a physical change. Water vapor in the air can change directly into ice when it touches a very cold window! A change of state from a gas to a solid is called depositing.
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.
Ice crystals form on a window when water vapor in the air becomes ice. This is caused by cooling. But mixing lettuce and salad dressing is not.