A Group 2 metal carbonate, MCO3\mathrm{MCO_{3}}MCO3, contains 8.11% carbon by mass. Relative atomic masses: C=12\mathrm{C} = 12C=12, O=16\mathrm{O} = 16O=16, Mg=24\mathrm{Mg} = 24Mg=24, Ca=40\mathrm{Ca} = 40Ca=40, Sr=88\mathrm{Sr} = 88Sr=88, Ba=137\mathrm{Ba} = 137Ba=137.
Which metal is M?
magnesium
calcium
strontium
barium
55 exam-style questions on Edexcel GCSE Chemistry 2.6 Calculations involving masses, covering 2.6.1 Relative formula mass and percentage composition, 2.6.2 Empirical and molecular formulae, 2.6.3 Conservation of mass, 2.6.4 Reacting masses and concentration in g dm⁻³, 2.6.5 The mole and the Avogadro constant, and 2.6.6 Limiting reactants and stoichiometry. Each one has a worked solution and a mark scheme showing where the marks go.