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

Splitting water molecules produces hydrogen gas, which is used to power machines through hydrogen fuel cells

 Splitting water molecules produces hydrogen gas, which is used to power machines through hydrogen fuel cells.

Explanation:  Electrolysis is a phenomenon in which the electrical energy is converted into the chemical energy. In the apparatus of the electrochemical cell, two electrodes are kept in the solution out of which one is positive electrode known as Anode and the other one is Cathode which is the negative electrode.

Thus in electrolysis , water molecules gets split and produces hydrogen gas which can be used in the power machines through hydrogen fuel cells.