What does the law of conservation of mass state?
a. mass cannot be created nor destroyed in a chemical reaction.
b. mass can be created and destroyed during a chemical reaction.
c. mass can be created but not destroyed in a chemical reaction.
d. mass can be destroyed but not created during a chemical reaction

Which of the following statements is true? a. most heat energy is easily recovered and used for useful actions. b. friction causes molecules to vibrate more slowly. burning air and gasoline in an c. engine changes chemical energy into mechanical energy. it is impossible to d. change mechanical energy into mechanical energy.