Question

what is chemical reaction? write an example

Answer 1

A reaction in which there is an irreversible change and which leads to the formation of entirely new substances by the rearrangement of atoms is termed as chemical reaction.
For example,
NH3 + HCl -> NH4Cl

Answer 2

Here is your answers

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another.[1] Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation.

Example of chemical reaction are

1 burning of candle

2 melting of wax