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Q74 (NDA-II/2021) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Applied everyday chemistry

To protect steel and iron from rusting, a thin layer of which one of the following metals is applied ?

Result
Your answer: —  Â·  Correct: B
Explanation

To protect steel and iron from rusting, a thin layer of zinc is applied through a process known as galvanization [1]. Zinc acts as a protective barrier, preventing moisture and oxygen from reaching the underlying metal. Furthermore, zinc provides cathodic or sacrificial protection; because zinc is more reactive (electronegative) than iron, it corrodes preferentially even if the coating is scratched or broken [1]. While other metals like magnesium and aluminium are used as sacrificial anodes in specific environments like water heaters or underwater structures, zinc is the standard metal applied as a thin surface layer for general galvanizing of steel and iron articles [1]. This method is highly effective and economical for extending the lifespan of iron structures such as bridges, railings, and car bodies [1][2].

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.5.1 Prevention of Corrosion > p. 54
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > 1.3.1 Corrosion > p. 13
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