Electrolysis Practice Exam 2026 – Comprehensive Test Prep Tool

In the process of electrolysis, an electric current is passed through an electrolyte, leading to the decomposition of compounds and the formation of new substances at the electrodes. In the case of the correct answer, the electrolysis of sodium chloride (saltwater) solution produces chlorine gas at the anode and hydrogen gas at the cathode. Additionally, sodium hydroxide is formed in the solution as a byproduct.

Sodium hydroxide (NaOH) is created because the sodium ions move to the cathode to gain electrons, forming sodium, which then reacts with water to produce sodium hydroxide. Meanwhile, the chloride ions are oxidized at the anode to produce chlorine gas, while water is reduced to produce hydrogen gas at the cathode.

The presence of both hydrogen and chlorine gas is significant in various applications, such as in chemical syntheses and industrial processes. The electrolysis of sodium chloride solution is a well-known and widely studied example, making this option particularly relevant and accurate within the context of electrolysis.

The other choices describe products that do not typically result from the electrolysis process under standard conditions. For instance, hydrogen peroxide is not a product of electrolysis in this scenario, nor is gold, which is generally not formed through this method.