Physics
Radioactivity and atomic physics — Topic 6
- 1.
A nucleus of uranium-238 (₉₂²³⁸U) decays by emitting an alpha particle. Write the nuclide notation of the resulting daughter nucleus, including its mass number and atomic number.
[3 marks] · no calculator - 2.
A radioactive isotope has a half-life of 5 days. A sample starts with an activity of 800 counts per minute. Calculate the activity after 20 days.
[3 marks] - 3.
Distinguish between alpha, beta and gamma radiation in terms of their penetrating power through materials.
[3 marks] · no calculator - 4.
A radioactive source is placed near a Geiger-Müller tube connected to a counter. Describe how the count rate can be used to determine the half-life of the source, including one correction that should be applied.
[4 marks] · no calculator - 5.
Complete the nuclear equation for the beta decay of carbon-14: ₆¹⁴C → ₇¹⁴N + [particle]. Identify the missing particle.
[3 marks] · no calculator - 6.
Explain one medical use of a gamma-emitting radioactive isotope, referring to why gamma radiation specifically is suitable.
[3 marks] · no calculator - 7.
Describe the structure of the atom in terms of the nucleus and electron arrangement, including the relative size of the nucleus compared to the whole atom.
[3 marks] · no calculator - 8.
Explain why alpha particles are more strongly ionising than gamma rays, and link this to their difference in penetrating power.
[3 marks] · no calculator - 9.
A sample initially contains 4.0 × 10¹⁰ radioactive nuclei. After 3 half-lives, calculate the number of radioactive nuclei remaining.
[3 marks] - 10.
Discuss one benefit and one risk associated with the use of radioactive isotopes in industry (e.g. checking the thickness of metal sheets).
[2 marks] · no calculator - 11.
Describe what happens during the nuclear fission of a uranium-235 nucleus, and explain how a chain reaction can occur.
[4 marks] · no calculator - 12.
Describe what happens during nuclear fusion, giving the Sun as an example, and state one difference between fusion and fission.
[3 marks] · no calculator - 13.
Discuss one advantage and one disadvantage of generating electricity using nuclear fission in a power station, compared with burning fossil fuels.
[2 marks] · no calculator - 14.
State three sources of background radiation, and identify which of these is typically the largest contributor.
[4 marks] · no calculator - 15.
State three safety precautions that should be taken when handling a radioactive source in a school laboratory.
[3 marks] · no calculator - 16.
A nucleus of radium-226 (₈₈²²⁶Ra) decays by emitting an alpha particle. Write the nuclide notation of the resulting daughter nucleus.
[3 marks] · no calculator - 17.
After emitting an alpha or beta particle, a nucleus is often left in an excited (higher-energy) state. Explain what happens when the nucleus subsequently emits a gamma ray, and state what happens to its mass number and atomic number.
[3 marks] · no calculator - 18.
A student records the count rate of a radioactive source, corrected for background radiation, over time: 400 counts/min at 0 minutes, 200 counts/min at 8 minutes, 100 counts/min at 16 minutes. Determine the half-life of the source.
[3 marks] - 19.
Explain why exposure to ionising radiation can be harmful to living cells, and state one possible long-term effect on the body.
[3 marks] · no calculator - 20.
Define the term isotope, and give an example of two isotopes of the same element, stating one way in which their properties differ and one way in which they are the same.
[4 marks] · no calculator