A student has a sample of each of four gases.
| Gas | Formula | Mass of sample in g |
|---|---|---|
| chlorine | Cl2\mathrm{Cl_{2}}Cl2 | 14.2 |
| ammonia | NH3\mathrm{NH_{3}}NH3 | 4.25 |
| carbon monoxide | CO\mathrm{CO}CO | 8.4 |
| nitrogen dioxide | NO2\mathrm{NO_{2}}NO2 | 9.2 |
Relative atomic mass (ArA_rAr): H = 1.0 C = 12.0 N = 14.0 O = 16.0 Cl = 35.5
Which gas sample contains the greatest number of molecules?
ammonia
carbon monoxide
nitrogen dioxide
chlorine
134 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.