A sealed glass tube contains only solid naphthalene. The tube is weighed, warmed until all the naphthalene has melted, then weighed again while still warm. Which row describes the two readings and the reason?
The readings are the same because no particles have entered or left
The second reading is lower because the liquid fills more of the tube
The second reading is higher because the warm particles move faster
The second reading is lower because some naphthalene became vapour
40 exam-style questions on AQA GCSE Physics 3.1 Changes of state and the particle model, covering 3.1.1 Density of materials and 3.1.2 Changes of state. Each one has a worked solution and a mark scheme showing where the marks go.