A student obtains these results after leaving identical potato cylinders in sugar solutions for the same time.
Table
| Sugar concentration / mol dm−3\text{mol dm}^{-3}mol dm−3 | Mean percentage change in mass / %\%% |
|---|---|
| 0.25 | +3.0 |
| 0.30 | +1.0 |
| 0.35 | -1.0 |
| 0.40 | -3.0 |
The student wants a more precise estimate of the concentration that gives no net mass change.
Which additional set of concentrations is most suitable?
0.100.100.10, 0.150.150.15, 0.200.200.20 and 0.25 mol dm−30.25\ \text{mol dm}^{-3}0.25 mol dm−3
0.310.310.31, 0.320.320.32, 0.330.330.33 and 0.34 mol dm−30.34\ \text{mol dm}^{-3}0.34 mol dm−3
0.350.350.35, 0.400.400.40, 0.450.450.45 and 0.50 mol dm−30.50\ \text{mol dm}^{-3}0.50 mol dm−3
0.200.200.20, 0.300.300.30, 0.400.400.40 and 0.50 mol dm−30.50\ \text{mol dm}^{-3}0.50 mol dm−3
41 exam-style questions on Edexcel GCSE Biology 1.4 Transport across cell membranes, covering 1.4.1 Transport into and out of cells and 1.4.2 Percentage gain and loss in osmosis. Each one has a worked solution and a mark scheme showing where the marks go.