Question

how can the rate of a reaction be decreased?
lowering the temperature
having more surface area
adding a catalyst
increasing the amount of reactants

Explanation:

• Lowering the temperature reduces the kinetic energy of reactant molecules. Fewer molecules have energy equal to or greater than the activation energy, so the frequency of effective collisions (which lead to reaction) decreases.
• Having more surface area (for solids in reactions) increases the reaction rate as more reactant particles are exposed for collision.
• Adding a catalyst provides an alternate reaction pathway with lower activation energy, increasing the reaction rate.
• Increasing the amount of reactants (if in the same physical state, e.g., for gases or solutions) increases the concentration. Higher concentration means more particles per unit volume, leading to more frequent collisions and higher reaction rate.

Answer:

lowering the temperature