Which observation shows that a change is chemical rather than physical?
Energy is transferred to or from the surroundings during the change
The arrangement and movement of the particles in the material change
The total mass of the closed system stays the same throughout
The original material does not form again when conditions are reversed
44 exam-style questions on OCR GCSE Physics 1.2 Changes of state, covering 1.2.1 Conservation of mass during changes of state, 1.2.2 Physical and chemical changes, 1.2.3 Heating, temperature and changes of state, 1.2.4 Specific heat capacity and specific latent heat, 1.2.5 Internal energy and temperature change, and 1.2.6 Energy transfer during a change of state. Each one has a worked solution and a mark scheme showing where the marks go.