What do these two changes have in common?
burning a candle
mixing glue and laundry powder to create putty
A: Both are caused by heating.
B: Both are only physical changes.
C: Both are chemical changes.
D: Both are caused by cooling.
Step 1: Think about each change.
Burning a candle is a chemical change. Both the wick and the melted wax burn. They react with oxygen in the air and turn into soot, carbon dioxide, and water.
Mixing glue and laundry powder to create putty is a chemical change. The putty is a different type of matter that was not there before the change.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Burning is caused by heating. But mixing glue and laundry powder to create putty is not.
Both are caused by cooling.
Neither change is caused by cooling.