Question

What must happen before a chemical reaction can begin?

Answer 1

The answer should be The activation energy must be reached.

Answer 2

The reactants need to reach activation energy.

Step-by-step explanation:

For a chemical reaction there need to be:

1.- The reactants ( the elements or compounds that are going to react).

2.- The activation energy (the necessary energy to start changing the matter in the interchange of atoms among the reactants).