A compound contains Fe3+\mathrm{Fe^{3+}}Fe3+ ions and O2−\mathrm{O^{2-}}O2− ions. Which formula is electrically neutral?
FeO\mathrm{FeO}FeO
Fe3O2\mathrm{Fe_{3}O_{2}}Fe3O2
Fe2O3\mathrm{Fe_{2}O_{3}}Fe2O3
FeO3\mathrm{FeO_{3}}FeO3
56 exam-style questions on Edexcel GCSE Chemistry 2.3 Ionic bonding, covering 2.3.1 Ions and the formation of ionic bonds, 2.3.2 Naming and deducing formulae of ionic compounds, and 2.3.3 Giant ionic lattices. Each one has a worked solution and a mark scheme showing where the marks go.