A company is developing ventilation filters containing nanoparticles of substance K. Substance K kills bacteria.
The filters contained the same mass of K and were tested under the same conditions.
| Filter | Mean diameter of K particles in nm | Percentage of bacteria surviving passage through the filter | Mass of K released into the air in mg |
|---|---|---|---|
| A | 20 | 9 | 0.8 |
| B | 80 | 28 | 0.2 |
Explain why a smaller percentage of bacteria survive passage through filter A.
Suggest why filter A could present a greater health risk than filter B.
Researchers found the following results from two previous safety studies.
| Study | Nanoparticle material | Exposure tested | Duration | Result |
|---|---|---|---|---|
| 1 | K | swallowed | 8 weeks | no harmful effect observed |
| 2 | M | breathed in | 10 years | no harmful effect observed |
Explain why these results do not show that nanoparticles of K are safe to breathe in over 10 years.
104 exam-style questions on AQA GCSE Chemistry 2.4 Bulk and surface properties of matter including nanoparticles, covering 2.4.1 Sizes of particles and their properties and 2.4.2 Uses of nanoparticles. Each one has a worked solution and a mark scheme showing where the marks go.