Question

Formation of rust when the iron is exposed to moist air is called ______

Answer 1

Hint: We have heard this sometimes that Iron and steel objects corrode very easily when they come in contact with oxygen in air, water or water vapors. A layer of rust is formed on the surface of iron or steel objects.

Complete answer: When iron and steel are exposed to oxygen in air and water or water vapors, a rust is formed on the surface of iron and steel objects. The process of formation of rust in presence of oxygen and water or water vapors is called rusting or corrosion.
Corrosion is the formation of metal oxides when iron is exposed to oxygen in air, or to moist air. Rust is Iron oxide. When an iron is exposed to moist air, it reacts with oxygen and forms rust \[(F{e_2}{O_3}\,.\,\,x{H_2}O)\] .
When the metals like steel and iron are placed under too much stress, it causes the material to crack. Cathodic protection makes the corrosion reaction thermodynamically unfavourable.
There are various methods to prevent corrosion are as follows:
Galvanization is one of the methods to prevent rusting of iron. It is the method of applying a protective layer on the surface of metal in order to prevent corrosion.
By using drying agents.
By using non- corrosive metals such as stainless steel or aluminium.
Formation of rust when the iron is exposed to moist air is called Corrosion.

Note:
Corrosion is also called rust formation. Rusting is an oxidation reaction. The iron reacts with water and leads to the formation of hydrated iron (III) oxide. The oxidation state of iron increases i.e. it attains \[ + 3\] oxidation state.