ron fences can be galvanised by coating them with a layer of zinc.When the layer of zinc is scratched exposing the iron to the weather, the iron doesnot rust.Explain why the exposed iron does not rust

The reason why the exposed iron does not rust is due to a process called "galvanic protection". When the layer of zinc is scratched and the iron is exposed, the zinc acts as a sacrificial anode.

Here are the steps explaining this process:

1. The zinc layer is more reactive than the iron. This means that zinc has a greater tendency to lose electrons than iron.

2. When the zinc layer is scratched, the zinc and iron come into contact with each other.

3. The zinc starts to corrode instead of the iron because it is more reactive. It loses its electrons to form zinc ions.

4. These electrons are then taken up by the iron, preventing it from rusting.

5. The zinc ions combine with oxygen and carbon dioxide in the air to form a protective layer of zinc carbonate. This layer further protects the iron from rusting.

6. This process continues until all the zinc is corroded. Only then will the iron start to rust.

So, the zinc layer not only acts as a physical barrier to prevent the iron from coming into contact with oxygen and water, but it also provides galvanic protection to the iron.