Figure: Part of a magnesium chloride structure

Which empirical formula is represented?
MgCl\mathrm{MgCl}MgCl
MgCl2\mathrm{MgCl_{2}}MgCl2
Mg2Cl\mathrm{Mg_{2}Cl}Mg2Cl
Mg2Cl3\mathrm{Mg_{2}Cl_{3}}Mg2Cl3
119 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.