A student uses two electronic balances to measure the mass of the same sealed bottle. The bottle is not opened between measurements.
| Measurement | Balance P in g | Balance Q in g |
|---|---|---|
| 1 | 52.14 | 52.16 |
| 2 | 52.20 | 52.17 |
| 3 | 52.18 | 52.16 |
| 4 | 52.16 | 52.15 |
Which conclusion is supported by the results?
Balance P gives the more reliable mean because its readings are more evenly spread around their mean.
Balance Q gives the mean with smaller uncertainty because its readings are closer together.
Both balances give means with the same uncertainty because each balance was used four times.
Balance P gives the mean with smaller uncertainty because its mean mass is greater.
95 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.