Why does a solution of higher concentration react more quickly?
Its particles each carry a larger amount of energy
Its particles are held together by stronger forces
Its particles have a lower activation energy to reach
Its particles are more crowded in the same volume
41 exam-style questions on AQA GCSE Chemistry 6.1 Rate of reaction, covering 6.1.1a Calculating rates of reactions, 6.1.1b Gradient of a tangent as rate, 6.1.2 Factors which affect the rates of chemical reactions, 6.1.3 Collision theory and activation energy, and 6.1.4 Catalysts. Each one has a worked solution and a mark scheme showing where the marks go.