Betty and her grandson decided to bake a cake. They gather eggs, flour, sugar, salt, baking soda, oil,
and vanilla. All of the ingredients are measured and
mixed following Betty's grandmother's recipe. They
bake the cake in the oven for 30 minutes. Did the
ingredients undergo a physical change or chemical
reaction? How do you know?

How is electrolysis most commonly used to produce an energy source? a - splitting water molecules produces oxygen, which organisms breathe to fuel their bodies. b - splitting water molecules produces hydrogen gas, which is used to power machines through hydrogen fuel cells. c - splitting carbon dioxide molecules produces coal, a form of carbon that can be burned to produce heat. d - splitting carbon dioxide molecules produces natural gas, which can be burned to generate electricity in power plants.