A teacher demonstrates the reaction of potassium with water. Potassium is stored under oil. It reacts violently with water, producing a flammable gas and a corrosive solution.
Which set of precautions gives the lowest risk?
Use a large piece so the reaction is clearly visible; wear eye protection; hold it with tweezers
Use a rice-grain-sized piece; stand behind a safety screen; handle it with tweezers, not fingers
Use a rice-grain-sized piece; warm the water first so it reacts quickly; wear eye protection
Use a rice-grain-sized piece; stand behind a safety screen; drop it into a test tube of water
230 exam-style questions on Edexcel GCSE Chemistry 1.1 Formulae, equations and hazards, covering 1.1.1 Formulae, word and balanced equations, 1.1.2 Balanced ionic equations, and 1.1.3 Hazard symbols and risk in practical work. Each one has a worked solution and a mark scheme showing where the marks go.