A pure compound has a known melting point of 110 ∘C110\,^\circ\mathrm{C}110∘C. A sample melts at 103–108 ∘C108\,^\circ\mathrm{C}108∘C. What does this suggest?
The sample contains impurities
The sample is a different pure compound
The compound has decomposed completely
The sample is pure
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.