During the electrolysis of water, which gas is produced at the cathode?

• A. Carbon dioxide (CO_2)
• B. Oxygen (O_2)
• C. Hydrogen (H_2)
• D. Nitrogen (N_2)

Answer: (C)

Verified step by step guidance

1. Understand that during the electrolysis of water, water molecules (H_2O) are split into their elemental gases at the electrodes.
2. Recall that the cathode is the electrode where reduction occurs, meaning it gains electrons.
3. At the cathode, water molecules gain electrons and are reduced to form hydrogen gas (H_2) and hydroxide ions (OH^-). The half-reaction is: \$2H_2O + 2e^- \rightarrow H_2 + 2OH^-$.
4. At the anode, oxidation occurs, where water molecules lose electrons to form oxygen gas (O_2) and hydrogen ions (H^+).
5. Therefore, the gas produced at the cathode during the electrolysis of water is hydrogen gas (H_2).