Question

What does the rusting of iron involves:
A. Oxidation
B. Reduction
C. Decomposition
D. Displacement

Answer 1

Rusting is defined as reddish-brown or reddish-yellow colour that coats iron or steel when exposed to air and moisture. Rusting of iron is the corrosion of iron.Example of rusting of iron can be a reddish-brown layer on iron rod and the chain of bicycle etc..

Complete step by step answer:
To answer this question first of all we should know the terms given in the question. So let’s start with the definition of rusting and rusting of iron :
Rusting: Rusting is defined as reddish-brown or reddish-yellow colour that coats iron or steel when exposed to air and moisture.
Rusting of iron: Rusting of iron is the corrosion of iron. Rusting of iron takes place when iron reacts with water and air.
Then we will talk about the reactions given in the options to check rusting of iron belongs to what.
Oxidation reaction: Those chemical reactions in which the oxidation number of atoms increases by losing the electrons are called oxidation reactions.
Reduction: Those chemical reactions in which the oxidation number of atoms decreases by gaining the electrons are called reduction reactions.
The reactions in which both the oxidation and reduction takes place simultaneously, are known as redox reactions.
Decomposition reaction: Those reactions in which the reactants break down into two or molecules are known as decomposition reactions.
Displacement reaction: Those reactions in which the one atom of a molecule is displaced by another atom or group of atoms.
Now if we see the reaction involved in the rusting of iron that is given as:
$4Fe{\text{ }} + {\text{ }}3{O_2}\; + {\text{ }}6{H_2}O{\text{ }} \to {\text{ }}4Fe{\left( {OH} \right)_3}$
In the reaction we can see that the oxidation number of iron increases from zero to three. Hence it will be an oxidation reaction.

So, the correct answer is Option A .

Note:
It can be seen as rusting involving oxidation. It may seem to you as a displacement reaction but it is actually an oxidation reaction in which the oxidation number of iron increases from $0$ to $3$ as $Fe$ to $F{e^{3 + }}$.