Question

Mention one example each for the different types of chemical reactions.

Answer 1

Chemical reactions are the processes in which one or more reactants are converted into one or more different products. In a chemical reaction, the constituent atoms of the reactants rearrange to form different products. Types of chemical reactions are:
Combination Reaction
Decomposition Reaction
Combustion Reaction
Single Displacement Reaction
Double Displacement Reaction

Complete step by step answer:
We will discuss the different types of reactions as mentioned above in detail.
Combination Reaction: In this reaction, two or more reactants combine to form a single product or multiple products.
Example: $S(s) + {O_2}(g) \to S{O_2}(g)$
(Sulphur combines with oxygen gas to form sulfur dioxide hence it is a combination reaction as two reactants combine to form a product)
Decomposition Reaction: In this type of reaction a single reactant is broken down into two or more products.
Example: $2{H_2}O(l) \to 2{H_2}(g) + {O_2}(g)$
(Water decomposes to form hydrogen gas and oxygen gas hence it is a decomposition reaction as a single reactant is broken down into two or more products)
Combustion Reaction: This reaction occurs when a compound combines with oxygen gas in the air. This process is known as burning.
Example: ${C_3}{H_8}(g) + 5{O_2}(g) \to 3C{O_2}(g) + 4{H_2}O(l)$
(Propane reacts with oxygen to give carbon dioxide gas and water. The product of this reaction is heat. Since propane combines with oxygen in this reaction, it is a combustion reaction.)
Single Displacement Reaction: In single displacement reactions, a more active element displaces another less active element from a compound.
Example: $Zn(s) + CuS{O_4}(aq) \to ZnS{O_4}(aq) + Cu(s)$
(Zinc displaces copper from copper sulfate in this solution hence zinc is a more reactive element than copper. Since a more active element displaces another less active element from a compound it is known as a single displacement reaction)
Double Displacement Reaction: In double displacement reactions two species are displaced instead of one. Most of the time in these reactions an insoluble solid or water is formed.
Example: $KCl(aq) + AgN{O_3}(aq) \to AgCl(s) + KN{O_3}(aq)$
(Since silver displaces potassium from potassium chloride and potassium displaces silver from silver nitrate hence it is an example of a double displacement reaction as two species are displaced instead of one.)

Note:
More than one reactant can also be formed in a combination reaction.
In a single displacement reaction given above copper cannot displace zinc, only vice versa is true.
If an insoluble solid is formed in a double displacement reaction it is called a precipitation reaction and if the water is formed then it is called a neutralization reaction.
In combustion reactions, the reactants are usually compounds containing carbon.