Question

Which of the following conditions are necessary for rusting of iron?
A) Presence of water only
B) Presence of air only
C) Presence of water and air both
D) None of these

Answer 1

‌ In the given question firstly we have to define the rust, it refers to , a usually reddish brown oxide formed by the reaction of iron and oxygen in the presence of water or air moisture. Talking about the process we get that it is where the iron comes in contact with water forms the anode and in contact with air forms the cathode.

Complete step by step solution:
The given question statement asks about the conditions necessary for rusting of iron. So we have to explain the rust and then mention the properties of therusting and then the reasons for that to happen over the iron surface. Now we have to mention the characteristics of rust.
Talking about the rust we get that rust is an iron oxide, a usually reddish brown oxide formed by the reaction of iron and oxygen in the presence of water or air moisture.
The process of rusting of iron is the one where the iron comes in contact with water forms the anode and in contact with air forms the cathode. At the anode, the atoms of iron are oxidized in order to form $F{e^{2 + }}$ , and at the cathode, the oxygen is reduced to water. Iron and steel rust whenever they come into contact with water and oxygen.
Therefore we can get that both the air and water are responsible for the causing of the rusting over the surface of iron.
Therefore the right option among the following would be option C, Presence of water and air both.

Note: Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Other forms of rust include the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in underwater concrete pillars, which generates green rust, is an example.