Why does seawater require distillation rather than ordinary filtration to make pure water?
Filtration removes the salt but not the microorganisms
Dissolved salt passes through filter paper
Seawater is too dense to pass through filter paper
Chlorine cannot be added to seawater
107 exam-style questions on Edexcel GCSE Chemistry 3.2 Methods of separating and purifying substances, covering 3.2.1 Pure substances and mixtures, 3.2.2 Techniques for separating mixtures, 3.2.3 Paper chromatography and Rf values, and 3.2.4 Making water potable. Each one has a worked solution and a mark scheme showing where the marks go.