A sample contains 3.20 g of methane, CH4\mathrm{CH_4}CH4.
Relative atomic masses: H = 1, C = 12
The Avogadro constant = 6.02 × 1023 per mole
Calculate the number of hydrogen atoms in the sample.
142 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.