Question

define chemical reaction ​

Answer 1

HIII

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. 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. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

Answer 2

Hello mate here is your answer~

Definition of Chemical reaction -A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another.
In the attached picture hydrogen (gas) reacting with another gas oxygen forms water which is a liquid and totally different from hydrogen and oxygen . Thus it is a chemical reaction