Question

Rusting of iron is a chemical reaction. The reaction can be termed as:
A.Combination reaction
B.Addition reaction
C.Both (A) and (B)
D.Decomposition reaction

Answer 1

Hint: A process in which two or more molecules react together to form products via rearrangement of ionic or molecular structure of the molecule, is known as chemical reaction. It can be of various types depending upon the type of interaction between the molecules.

Complete answer:
Major types of chemical reactions:
Combination reactions- These reactions are also termed as addition reactions. When the atoms of two or more compounds combine together to form a single product, then the reaction is known as combination reaction. It is generally represented as \[A + B \to AB\].
Example: \[{H_2} + \frac{1}{2}{O_2} \to {H_2}O\]
Decomposition reactions- When a single compound is separated into two or more than two products then the reaction is termed as decomposition reaction. It is exactly opposite of the combination reaction. It is generally represented as \[AB \to A + B\].
Example: \[CaC{O_3} \to CaO + C{O_2}\]
Displacement reaction- A reaction in which an element which is more electronegative, displaces the less electronegative element from salt of its aqueous solution is termed as displacement reaction. It is generally represented as \[A + XY \to AY + X\]
Example: \[Zn + CuS{O_4} \to ZnS{O_4} + Cu\]
Double-Displacement reactions- A reaction in which exchange of ions between the reactants take place, is termed as double-displacement reaction. It is generally represented as \[AB + XY \to AY + XB\].
Example: \[N{a_2}S + 2HCl \to 2NaCl + {H_2}S\]
The oxidative attack of air and moisture on the surface of iron, due to which formation of an oxide of iron takes place which is termed as rust and the phenomenon is known as rusting. The chemical reaction involved in the process is represented as follows:
\[4Fe + 2{H_2}O + 3{O_2} \to 2F{e_2}{O_3} \cdot {H_2}O\]
Hence it is a combination reaction.

Therefore, the correct answer is option (C).

Note:
Oxidation reaction: When there is an increase in the oxidation state of any element during a reaction, it is termed as oxidation reaction. Rusting of iron can also be stated as an oxidation reaction because during the process, the oxidation state of iron is increasing.