OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P6.1 Radioactive Emissions Exam Questions
Free OCR GCSE Physics A exam questions for P6.1 Radioactive Emissions, with a mark scheme for every pack. Covers Atoms and isotopes, unstable nuclei, alpha, beta, gamma and neutron emissions, ionising and penetrating power, nuclear equations and half-life.
P6.1 Radioactive Emissions exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Physics A P6.1 Radioactive Emissions
P6.1 opens the P6 Radioactivity chapter of OCR Gateway Physics A. It builds on the atomic model from P1.1 to explain why some nuclei are unstable and decay randomly, emitting alpha particles, beta particles, gamma rays or neutrons. You need to compare their ionising and penetrating powers, balance nuclear equations using mass number and atomic number, and describe how electrons can change orbit when they absorb or emit radiation. The topic introduces activity, count rate and half-life, and the random nature of decay. It leads into P6.2 on uses and hazards. Examiners frequently test nuclear equations, half-life from graphs and penetration comparisons.
What you need to know
- Isotopes Atoms of the same element have the same number of protons. Isotopes have different numbers of neutrons. Some isotopes have unstable nuclei.
- Electron energy levels Electrons can move to a higher energy level by absorbing EM radiation and move to a lower level by emitting it. An atom that loses an electron becomes a positive ion.
- Types of emission Alpha: 2 protons and 2 neutrons, most ionising, stopped by paper. Beta: high speed electron from the nucleus, stopped by aluminium. Gamma: EM radiation, least ionising, reduced by thick lead. Neutrons can also be emitted.
- Nuclear equations In alpha decay the mass number falls by 4 and the atomic number by 2. In beta decay a neutron becomes a proton, so the atomic number rises by 1 and mass number is unchanged. Gamma emission changes neither.
- Random decay Radioactive decay is random: you cannot predict which nucleus will decay next, but you can predict the behaviour of a large number.
- Half-life The time for the number of nuclei of the isotope in a sample, or its activity, to halve. Activity is measured in becquerels.
Common mistakes in P6.1 Radioactive Emissions
- Saying gamma is the most ionising. Alpha is the most ionising, gamma the most penetrating.
- Saying the beta particle is an electron from the shells. It comes from the nucleus when a neutron changes into a proton.
- Changing mass number in beta decay. It stays the same.
- Saying half-life is half the time for the sample to fully decay.
- Saying decay can be sped up by heating. Radioactive decay is not affected by temperature.
Try three P6.1 Radioactive Emissions exam-style questions
1. Uranium-238 (atomic number 92) emits an alpha particle to become thorium. State the mass number and atomic number of thorium. (2 marks)
Show the mark scheme answer
Mass number = 234; atomic number = 90.
2. A sample has an activity of 640 Bq. Its half-life is 3 days. Calculate its activity after 12 days. (3 marks)
Show the mark scheme answer
12 / 3 = 4 half-lives; 640 / 2^4 = 640 / 16; = 40 Bq.
3. Compare the penetrating and ionising properties of alpha and gamma radiation. (4 marks)
Show the mark scheme answer
Alpha is highly ionising; but has low penetration, stopped by paper or a few cm of air; gamma is weakly ionising; but highly penetrating, only reduced by thick lead or concrete.
P6.1 Radioactive Emissions FAQs
What does OCR GCSE Physics A (Gateway Science) P6.1 Radioactive Emissions cover?
It covers isotopes, electron energy levels, alpha, beta, gamma and neutron emissions, nuclear equations, random decay and half-life.
Which paper is P6.1 examined on?
Topics P5 to P8 are assessed on Paper 2 (Foundation) or Paper 4 (Higher), which can also draw on knowledge from P1 to P4 and practical skills.
How do I balance a nuclear equation?
Make sure the mass numbers on the top add up to the same total on both sides and the atomic numbers on the bottom do too, using the correct symbols for alpha and beta particles.
