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Q91 (CDS-I/2023) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Applied everyday chemistry Answer Verified

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

Result
Your answer: —  Â·  Correct: C
Explanation

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
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