Which gas is produced by the electrolysis of water?

The correct answer is hydrogen and oxygen, as these are the products formed during the electrolysis of water. In this process, an electric current is passed through water (H₂O), leading to its decomposition into its elemental components.

At the anode (the positive electrode), oxygen is generated as water molecules lose electrons and are oxidized. This reaction produces O₂ gas. Simultaneously, at the cathode (the negative electrode), hydrogen ions gain electrons, resulting in the formation of H₂ gas.

The balanced chemical equation for this reaction can be represented as:

2 H₂O (l) → 2 H₂ (g) + O₂ (g).

This demonstrates that for every two molecules of water decomposed, two molecules of hydrogen gas and one molecule of oxygen gas are produced. Therefore, the electrolysis of water is a straightforward method to obtain both hydrogen and oxygen gases, which is essential for various applications, including fuel cell technology and in laboratory settings.