A reaction is carried out at 20 ∘C20\ ^\circ\text{C}20 ∘C and then repeated at 40 ∘C40\ ^\circ\text{C}40 ∘C. Which statement about the reacting particles at 40 ∘C40\ ^\circ\text{C}40 ∘C is correct?
The particles are larger, so they collide more often
The particles have less energy, so fewer of them react
The particles move faster, so they collide more often
The particles need more energy before they can react
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.