The method of protecting steel and iron from rusting by coating them with a thin layer of zinc is called ______?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Galvanisation
Iron rusts when it is in contact with air and moisture. Galvanisation is the coating of iron or steel with a thin layer of zinc. The zinc keeps air and water away, and since zinc is more reactive than iron, it corrodes first and protects the iron even where the coating is scratched.
Why the other options are incorrect
Option (1) Alloying — Incorrect. It is mixing a metal with other elements, as iron with chromium and nickel makes stainless steel; there is no coating.
Option (3) Anodising — Incorrect. It builds a thick oxide layer on aluminium by electrolysis, not a zinc layer on iron.
Option (4) Greasing — Incorrect. It covers iron with a film of grease or oil to keep moisture out, as on machine parts.