Question

Statement I: Rusting of iron can be prevented by forming a layer of the substance that is chemically inert to the atmosphere.
Statement II: The inert layer prevents the metal from interacting with the atmosphere.

• A. Statement I:- True Statement II:- True
• B. Statement I:- True Statement II:- False
• C. Statement I:- False Statement II:- False
• D. Statement I:- False Statement II:- True

Answer 1

The correct option is A

Statement I:- True

Statement II:- True

Barrier Protection:- Rusting of iron happens when iron reacts with oxygen ($O_2$) and moisture ($H_{2}O$) from the atmosphere. Hence rusting can be prevented by cutting off the surface of the metal from getting exposed to the atmosphere. This is done by some methods like painting, oiling, greasing, etc. where a layer of different substance is coated on the metal surface to prevent it to further react with the external atmosphere. It is essential that the external coating is inert to atmosphere.

Sacrificial Protection:- In this, a layer of more reactive metal is introduced over the surface of the metal such as in galvanization (layer of more reactive metal zinc is introduced over iron) and zinc reacts with atmosphere instead of iron and protects it from corrosion.