What is renewable energy? A. Energy that will not be regenerated in our lifetime.

B. Energy that will never be used up.

C. Energy that take millions of years to form.

D. Energy that is inexpensive but produce harmful waste
products

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.