Electrolysis breaks down water to form hydrogen and oxygen gas. the word equation that represents this reaction is: water

When a reduction reaction and an Oxidation reaction takes place due to passing of current through water the molecules of water split into the compounds. Where it is made up of hydrogen in its state of gas and also Oxygen in its state of gas this method is most vastly is known as electrolysis.

In this process a certain direct current is passed from inside water. This direct current value can be near about 1.23 voltages the reaction that happens inside is given below.

           2 Water---> Oxygen + 4 hydrogen ions + 4 Electrons

            2 Hydrogen ions + 2 electrons > hydrogen gas  

a corroding iron, if that's one of your choices

answer carbon and three oxygen atoms;