Question

In electrolysis of water, why is the volume of gas collected over one electrode double the volume of gas collected over the other electrode?

• A. Because cathode is stronger than anode
• B. Because oxygen is twice as hydrogen
• C. Because hydrogen is twice as oxygen
• D. Because oxygen is more electronegative.

Answer 1

The correct option is C Because hydrogen is twice as oxygen

We usually perform electrolysis to split the constituents of water. Water is composed of 2 atoms of H and 1 atom of O. Therefore the amount of H is double than that of O. The two electrodes collect $H_2$ and $O_2$ separately, therefore, the volume of gas collected in one electrode is double the volume of gas collected in the other electrode.