A technician must select, from the four samples in the table, the sample containing the fewest atoms.
Relative atomic mass (ArA_rAr): H = 1.0 He = 4.0 C = 12.0 N = 14.0 O = 16.0
| Sample | Substance | Mass |
|---|---|---|
| P | carbon monoxide, CO\mathrm{CO}CO | 2.8 g |
| Q | nitrogen dioxide, NO2\mathrm{{NO_2}}NO2 | 4.6 g |
| R | water, H2O\mathrm{H_2O}H2O | 3.6 g |
| S | helium, He\mathrm{He}He | 2.0 g |
Which sample should the technician select?
Sample P
Sample Q
Sample R
Sample S
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.