Solutions P and Q react, causing the mixture to change colour. Equal volumes of the solutions are mixed at the same temperature.
The colour change takes longer when a more dilute solution P is used.
Which statement explains why?
The dilute mixture makes more product, so the colour change takes longer to complete.
The P particles are farther apart, so collisions with Q particles happen less frequently.
P and Q collide equally often, but successful collisions take longer to react.
Dilution decreases the surface area of solution P that is exposed to solution Q.
122 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.