Question

A decomposition reaction is the opposite of a combination reaction. Explain with the help of an example.

Answer 1

The reaction in which a compound breaks down to give two or more simpler substances is called a decomposition reaction.
For example, on passing an electric current through water in which a small amount of sulphuric acid has been added, water decomposes to give hydrogen and oxygen gases.
2H₂O → 2H₂ + O₂

The reaction in which two or more elements combine to form a single compound is called a combination reaction.
For example, hydrogen combines with oxygen to form water.
2H₂ + O₂ → 2H₂O

From the above examples, it is clear that a decomposition reaction is the opposite of a combination reaction.