A scientist records the particles in two samples before and after a change. Each capital letter represents a different type of atom, and a hyphen joins atoms in the same particle.
The scientist's records are shown in the table.
| Change | Particles before the change | Particles after the change |
|---|---|---|
| R | A-B particles close together in a random arrangement | A-B particles far apart |
| S | C-C particles mixed with D-D particles | C-D particles |
State whether each change is physical or chemical. Explain each decision using the particle records.
During change R, the liquid sample is heated and bubbles are seen. A student says that the bubbles prove that R is a chemical change.
Explain why the student is wrong.
After change R, the scientist draws each A-B particle as a larger circle than before, because the particles are farther apart.
Explain why this drawing is incorrect.
93 exam-style questions on OCR GCSE Chemistry 1.1 The particle model, covering 1.1.1 The particle model and changes of state and 1.1.2 Limitations of the particle model. Each one has a worked solution and a mark scheme showing where the marks go.