What do these two changes have in common?
making paper from wood
silver jewelry tarnishing

 - Both are caused by cooling.
 - Both are caused by heating.
 - Both are only physical changes.
 - Both are chemical changes.
Step 1: Think about each change.
Making paper from wood is a chemical change. Paper is made by mixing tiny pieces of wood with special chemicals. The wood reacts with the chemicals to form pulp. Wood and pulp are different types of matter.
Metal turning less shiny over time is called tarnishing. Silver jewelry tarnishing is a chemical change. The silver reacts with sulfur in the air to form black tarnish. The tarnish 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.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.