Question 22N.2.HL.TZ0.b.iii
| Date | November 2022 | Marks available | [Maximum mark: 3] | Reference code | 22N.2.HL.TZ0.b.iii |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Discuss | Question number | b.iii | Adapted from | N/A |
Polonium-210 (Po-210) decays by alpha emission into lead-206 (Pb-206).
The following data are available.
Nuclear mass of Po-210 = 209.93676 u
Nuclear mass of Pb-206 = 205.92945 u
Mass of the alpha particle = 4.00151 u
In the decay of polonium−210, alpha emissions can be accompanied by the emissions of gamma photons, all of the same wavelength of 1.54 × 10−12 m.
Discuss how this observation provides evidence for discrete nuclear energy levels.
[3]
photon energy is determined by its wavelength ✓
photons are emitted when nucleus undergoes transitions between its «nuclear» energy levels
OR
photon energy equals the difference between «nuclear» energy levels ✓
photons have the same energy / a fixed value
OR
energy is quantized / discrete ✓
Many identified conservation of momentum and consequently the relative velocities but it was common to miss MP3 for correctly relating this to KE.
