Why does the galvanization of iron (coating with zinc) prevent rusting even if the outer zinc layer is scratched and iron is exposed to the atmosphere?

Answer and explanation

Correct answer: B. Zinc has a more negative reduction potential than iron and oxidizes preferentially as sacrificial anode

  1. Step 1: Standard reduction potentials are: and .
  2. Step 2: Because zinc has a more negative reduction potential, it has a greater oxidation potential and loses electrons more readily than iron ( is more electropositive).
  3. Step 3: When galvanized iron is scratched, an electrochemical cell is formed in which zinc acts as the sacrificial anode: .
  4. Step 4: The electrons flow to the iron, which acts as the cathode where atmospheric oxygen is reduced (), preventing iron from being oxidized to .
Answer
Zinc has a more negative standard reduction potential than iron and acts as a sacrificial anode, oxidizing preferentially
Why not the others: 'Zinc forms an insoluble covalent network...' is false because zinc provides cathodic protection electrochemically; 'Zinc absorbs all moisture...' is incorrect as zinc does not act as a desiccant; 'Iron converted into gold...' is medieval alchemy.

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