Factors that Increase Reaction Rate

Steps:

• Identify factors speeding up reactions: higher temperature, concentration, surface area, or catalysts per collision theory.
• Assume standard options: 1 decreases temperature (slows rate), 2 decreases concentration (slows rate), 3 adds catalyst (increases rate), 4 increases surface area (increases rate).
• Evaluate combinations: A pairs slowing factor 1 with 3; B pairs slowing 2 with 4; C pairs both speeding 3 and 4; D omits 3.
• Select C as it includes only rate-increasing changes.

Why C is correct:

• Catalysts lower activation energy and increased surface area boosts collisions, both accelerating reactions per rate law definitions.

Why the others are wrong:

• A includes 1, which reduces kinetic energy and slows collisions.
• B includes 2, which lowers reactant particle frequency and decreases rate.
• D ignores 3, missing a key catalyst effect on activation energy.

Final answer: C