Iron is used in bridges and automobiles to provide strength. However, iron tends to corrode and rust. A layer of which of the following metal can be used for prevention from rust and corrosion?

Zinc

The correct answer is option 4. Zinc.

Galvanization is a process used to protect iron and steel from corrosion by applying a layer of zinc to the surface. Zinc acts as a sacrificial anode, providing a protective barrier against rust and corrosion. Here's how galvanization works:

1. Formation of Zinc Layer:

In the galvanization process, the iron or steel object is immersed or coated with molten zinc.

Alternatively, a layer of zinc can be applied through a process known as electroplating, where zinc is deposited onto the metal surface through an electrolytic process.

2. Zinc as a Sacrificial Anode:

Zinc has a higher affinity for oxidation compared to iron. In the presence of moisture and oxygen, zinc undergoes oxidation preferentially over iron.

The zinc layer essentially becomes a sacrificial anode, corroding in place of the iron or steel substrate.

3. Formation of Zinc Oxide:

As zinc undergoes oxidation, it forms zinc oxide (ZnO), a white corrosion product. Zinc oxide provides a protective layer that acts as a barrier, preventing further corrosion of the underlying iron or steel.

4. Advantages of Galvanization:

Extended Lifespan: Galvanization significantly extends the lifespan of iron and steel structures by offering effective corrosion protection.

Uniform Coating: The zinc layer provides uniform coverage, even in hard-to-reach areas, ensuring comprehensive protection.

5. Common Applications:

Galvanization is widely used in various industries, including construction, automotive, and infrastructure.

It is commonly employed in the production of bridges, pipelines, fencing, automobile chassis, and other structures where corrosion resistance is essential.

6. Comparison with Other Metals:

While other metals like aluminum and chromium also provide corrosion resistance, zinc is often preferred for its cost-effectiveness and sacrificial anode properties.

In summary, the use of a zinc layer through galvanization helps protect iron and steel from rust and corrosion, ensuring the longevity and structural integrity of various applications in construction and manufacturing.