Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Changing the shape of an elastic material gives it potential energy.

A: Changing the shape of an elastic material gives it what type of energy?
****
Q: In the lungs, oxygen diffuses out of the alveoli and into capillaries.

A: In the lungs, oxygen diffuses out of the alveoli and into where?
****
Q: Copper oxide substance is created when a copper turns from reddish brown to greenish brown.

A:
What substance is created when a copper turns from reddish brown to greenish brown?
****