Question

Iron is galvanized by coating it with:
A.nickel
B.chromium
C.copper
D.zinc

Answer 1

Hint: We all heard about rusting of iron. In common language, the red layer that has appeared in the iron surface when it is kept for a long time in open is termed as rusting of iron. Rusting destroys the metal so it is very necessary for us to prevent rusting.

Complete answer:
First we discuss the science behind the rusting of iron in detail. When iron is exposed to oxygen in presence of moisture, it leads to rust formation. The reaction of rusting is not instantaneous. The reaction of iron and oxygen produces iron oxide which weakens the bond between iron atoms. The chemical reaction of formation of rust is shown below:

$4{\rm{Fe}} + 3{{\rm{O}}_{\rm{2}}} + 2x{{\rm{H}}_{\rm{2}}}{\rm{O}} \to {\rm{2F}}{{\rm{e}}_2}{{\rm{O}}_{\rm{3}}}x{{\rm{H}}_{\rm{2}}}{\rm{O}}$

The above reaction indicates that reaction of iron, oxygen and water produces hydrated iron (III) oxide (rust).
As rusting makes iron weak, flasky, degradation of its strength, its appearance, it is very important to prevent rusting. There are various methods, such as, galvanization, cathodic protection, coating etc.
Now, we discuss galvanization in detail. Galvanization is the method in which a layer of protection of zinc is applied on a metal. It is one common method of prevention of rusting. It is one common method of prevention of rusting. In this method, the metal in which rusting is to be prevented is dipped in molten zinc by the process of electroplating. Zinc gives cathodic protection to the surface of iron by acting as an anode.

Hence, the correct option is D, that is, zinc.

Note: The disadvantage of galvanization is that its protection from corrosion is limited to a certain period of time since the layer of zinc is eaten up in the rusting.