Question

what must happen before a chemical reaction can begin?
the activation energy must be exceeded.
the activation energy must be reached.
the concentrations of products and reactants must be equal.
the concentration of reactant molecules must be reduced.

Explanation:

• Activation energy is the minimum energy required for a chemical reaction to occur. So, the activation energy must be reached.
• When the concentrations of products and reactants are equal, the reaction is at equilibrium, not at the start.
• Reducing the concentration of reactant molecules doesn't start the reaction; it affects the rate.

Answer:

The activation energy must be reached.