Catalysts lower activation energy in reactions

Steps:

• Identify activation energy as the minimum energy barrier for reactants to form products.
• Recall that catalysts provide an alternative pathway with lower energy requirements.
• Evaluate each option: only catalysts directly affect the energy barrier.
• Confirm the choice by linking to reaction kinetics principles.

Why A is correct:

• A catalyst decreases activation energy by offering a lower-energy reaction pathway, as defined in transition state theory.

Why the others are wrong:

• B: Decreasing temperature slows reaction rate but does not change activation energy.
• C: Increasing concentration raises collision frequency, affecting rate but not activation energy.
• D: Increasing pressure shifts equilibrium for gases but leaves activation energy unchanged.

Final answer: A