Which one of the following is not true for anodizing process?

Anodizing is an electrochemical process that thickens the natural oxide layer on metals like aluminium, titanium, and magnesium to enhance corrosion resistance [1]. During the process, the metal article (such as aluminium) is made the anode in an electrolytic cell containing an acid electrolyte [1]. When an electric current is applied, oxygen gas is evolved at the anode, not the cathode [1]. This oxygen reacts with the aluminium surface to form a durable, protective layer of aluminium oxide [1]. Hydrogen gas is typically evolved at the cathode during this electrolysis. Because it creates lightweight, durable, and corrosion-resistant components, anodizing is extensively used in the aircraft industry [3]. Therefore, the statement claiming oxygen is evolved at the cathode is incorrect, making option 3 the right choice.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > p. 42
2. [3] https://en.wikipedia.org/wiki/Anodizing