A scientist tests cube-shaped silver particles of different sizes against bacteria.
The same mass of silver is used each time.
| Side length of particle (nm) | Surface area to volume ratio | Time to kill 99% of the bacteria (minutes) |
|---|---|---|
| 5 | 1.2 | 4 |
| 10 | 0.6 | 8 |
| 20 | 0.3 | 16 |
| 100 | 0.06 | 80 |
Which conclusion is supported by the data?
The time taken is directly proportional to the surface area to volume ratio.
Particles with a side length of 100 nm do not kill any of the bacteria.
Halving the side length of the particles doubles the time taken.
Doubling the surface area to volume ratio halves the time taken.
122 exam-style questions on OCR GCSE Chemistry 2.3 Properties of materials, covering 2.3.1 Carbon bonding and the variety of organic compounds, 2.3.2 Diamond, graphite, fullerenes and graphene, 2.3.3 Bond strength, changes of state and predicting states, 2.3.4 Bulk properties and types of bonding, and 2.3.5 Nanoparticles: scale, surface area, uses and risks. Each one has a worked solution and a mark scheme showing where the marks go.