44 exam-style questions on OCR GCSE Physics 1.1 The particle model, covering 1.1.1 Development of the atomic model, 1.1.2 Structure of the atom, 1.1.3 The size of atoms and small molecules, 1.1.4 Density, 1.1.5 Density and the states of matter, and 1.1.6 Density, mass and volume. Each one has a worked solution and a mark scheme showing where the marks go.