Ammonium chloride has the formula NH4Cl\mathrm{NH_{4}Cl}NH4Cl.
Sodium phosphate has the formula Na3PO4\mathrm{Na_{3}PO_{4}}Na3PO4.
What is the formula of ammonium phosphate?
NH4PO4\mathrm{NH_{4}PO_{4}}NH4PO4
NH4(PO4)3\mathrm{NH_{4}(PO_{4})_{3}}NH4(PO4)3
(NH4)3PO4\mathrm{(NH_{4})_{3}PO_{4}}(NH4)3PO4
(NH4)3(PO4)3\mathrm{(NH_{4})_{3}(PO_{4})_{3}}(NH4)3(PO4)3
55 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.