A student heats 2.4 g of magnesium in a crucible until all of it has reacted. The solid left has a mass of 4.0 g. Which statement explains the increase in mass?
Oxygen from the air has combined with the magnesium.
The magnesium atoms have expanded on being heated.
Carbon dioxide from the air has been absorbed by the solid.
Some of the magnesium has escaped as a white smoke.
39 exam-style questions on AQA GCSE Chemistry 4.1 Reactivity of metals, covering 4.1.1 Metal oxides, 4.1.2 The reactivity series, 4.1.3 Extraction of metals and reduction, and 4.1.4 Oxidation and reduction in terms of electrons. Each one has a worked solution and a mark scheme showing where the marks go.