Question

Galvanized Iron (GI) sheets are coated with :

• A. Sn
• B. Ni
• C. Cu
• D. Zn

Hint:

{G}alvanization = Coating iron with {Z}inc ({Zn}). Remember the "Z" in Zinc for galvani{z}ation. Zinc acts as a protective layer and also "sacrifices" itself to prevent the iron from rusting if the coating is damaged.

Answer 1

The Correct Option is D

Concept: Galvanization is a process of applying a protective coating to iron or steel to prevent rusting (corrosion). Step 1: Understanding Galvanization Rusting is the corrosion of iron due to its reaction with oxygen and moisture in the atmosphere, forming hydrated iron(III) oxide. Galvanization is a common method to protect iron from rusting. The process involves coating the iron or steel with a layer of another metal. Step 2: The Metal Used in Galvanization The metal most commonly used for galvanizing iron is Zinc (Zn). The process typically involves dipping the iron or steel object into molten zinc (hot-dip galvanizing) or using electroplating to deposit a zinc layer. Step 3: How Zinc Protects Iron Zinc protects iron in two main ways: \begin{enumerate} % Option („) Barrier Protection: The zinc coating forms a physical barrier that prevents oxygen and water from reaching the iron surface. % Option (…) Sacrificial Protection (Cathodic Protection): Zinc is more reactive than iron (it is higher in the electrochemical series). If the zinc coating is scratched or broken and the iron is exposed, the zinc will corrode preferentially (acts as a sacrificial anode) instead of the iron. The zinc "sacrifices" itself to protect the iron. Step 4: Analyzing the options
(1) Sn (Tin): Coating iron with tin is called "tinning" (e.g., tin cans). Tin protects iron mainly by barrier protection. If the tin coating is scratched, the iron underneath can rust rapidly because iron is more reactive than tin (tin provides cathodic protection to iron only in certain environments, but generally, iron is anodic to tin).
(2) Ni (Nickel): Nickel plating can also protect iron, usually by electroplating.
(3) Cu (Copper): Copper plating can be used, but copper is less reactive than iron. If the copper coating is scratched, the iron will corrode.
(4) Zn (Zinc): This is the metal used for galvanization, providing both barrier and sacrificial protection. Therefore, galvanized iron sheets are coated with zinc.