In corrosion protection, which metal is commonly used for galvanizing iron to prevent rusting?

Introduction / Context:
Galvanizing is a widely used method to protect iron and steel from rusting. In everyday life, we encounter galvanized iron sheets in roofing, fences, poles and many structural applications. Examination questions often ask which specific metal is coated onto iron during galvanization, as this reflects basic understanding of corrosion prevention and electrochemistry in materials science.

Given Data / Assumptions:

• The process mentioned is ‘‘galvanizing iron’’. • Options include zinc, lead, aluminium and copper. • We assume the context is hot-dip galvanizing used for iron and steel.

Concept / Approach:
In galvanizing, iron or steel articles are coated with a layer of zinc. Zinc acts as a protective barrier and also provides sacrificial protection because it is more reactive than iron. If the coating is damaged, zinc tends to corrode preferentially, thereby protecting the underlying iron. Therefore, the metal used in the galvanizing process is zinc, not lead, aluminium or copper.

Step-by-Step Solution:
1. Recall that galvanization refers to coating iron or steel with another metal to prevent rusting. 2. The most common industrial method is hot-dip galvanizing in molten zinc. 3. Zinc forms a tightly adhering and protective layer on the surface. 4. If the coating is scratched, zinc continues to protect because it is anodic relative to iron. 5. Among the options provided, only zinc matches this standard description of galvanizing iron.
Verification / Alternative check:
Engineering and chemistry references clearly describe galvanized iron sheets as being coated with zinc. The abbreviation ‘‘GI sheet’’ often denotes zinc-coated steel. Other corrosion protection methods include tin plating, chromium plating and painting, but these are not referred to as ‘‘galvanizing’’ in the strict sense. This corroborates that zinc is the correct answer.

Why Other Options Are Wrong:
Option B, ‘‘Lead’’, is used in some alloys and protective coatings but is not the metal used in standard galvanization of iron. Option C, ‘‘Aluminium’’, can be used in aluminizing processes, which are different from galvanizing. Option D, ‘‘Copper’’, is used in electrical wiring and decorative coatings but is more noble than iron and would not offer sacrificial protection. Therefore, these options do not match the established meaning of galvanizing.

Common Pitfalls:
Students sometimes mix up different anti-corrosion methods and think that any metal coating may be called galvanizing. Another pitfall is confusing tin plating of food cans with galvanization of structural steel. Remember the key association: galvanizing iron means coating it with zinc to prevent rusting through both barrier and sacrificial protection mechanisms.

Final Answer:
For galvanizing iron, the metal commonly used is zinc.