A remote visitor centre takes fresh water from a nearby lake. The untreated water contains suspended soil particles and harmful microbes.
For treated water to be safe to drink at the centre:
The table shows the results for three samples of treated water.
| Sample | Concentration of dissolved salts in mg/dm3\text{mg/dm}^3mg/dm3 | Number of harmful microbes detected in 100 cm3 |
|---|---|---|
| P | 320 | 0 |
| Q | 680 | 0 |
| R | 210 | 7 |
Using the safety limits and the results in the table, give the sample that is potable.
Name the treatment step used to remove the suspended soil particles from the untreated lake water.
Name the treatment step used to reduce the harmful microbes to safe levels.
A second water source contains a high concentration of dissolved salts.
The treatment plan states:
'Use the treatment named in part (b) to remove the dissolved salts.'
Give one error in this treatment plan.
87 exam-style questions on AQA GCSE Chemistry 10.1 Using the Earth's resources and obtaining potable water, covering 10.1.1 Using the Earth's resources and sustainable development, 10.1.2 Potable water, 10.1.3 Waste water treatment, and 10.1.4 Alternative methods of extracting metals. Each one has a worked solution and a mark scheme showing where the marks go.