Question

Which of the following method cannot prevent corrosion?

• A. Keeping the metal in sunlight
• B. Covering the surface with paint, grease, oil etc.
• C. Galvanisation
• D. By cathodic protection

Answer 1

The correct option is A Keeping the metal in sunlight

Prevention of Corrosion:

Using paint or some chemicals: Prevent the surface of the metallic object to come in contact with the atmosphere. It is done by covering the surface with paint, grease, oil or some chemicals (bisphenol).

Protective coating: By covering the material surface by other metals $Sn,Zn$ etc. that are inert or react
to save the material. Steel objects that must withstand the weather are coated with a layer of zinc. This process is called galvanisation.

Cathodic protection:A technique to control corrosion of a metal surface by making it work as a cathode of an electrochemical cell by placing in contact with the metal that is more easily oxidised (like zinc).

Keeping the metal in sunlight cannot prevent corrosion.