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:

To determine what must happen before a chemical reaction begins, we analyze each option:

• Option 1: Exceeding activation energy is not necessary; reaching it is enough for the reaction to start.
• Option 2: Activation energy is the minimum energy required for reactant molecules to undergo a reaction. So, the activation energy must be reached for the reaction to begin.
• Option 3: Equal concentrations of products and reactants is a state of equilibrium, not a prerequisite for a reaction to start.
• Option 4: Reducing reactant concentration would hinder, not initiate, a reaction.

Answer:

B. The activation energy must be reached.