plumiConservation laws and particle equations: Edexcel International A Level Physics questions
Edexcel International A Level Physics past-paper questions on 4.5.2.4 Conservation laws and particle equations, 2019–2025, with mark schemes and examiner’s reports where available.
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Q14(a)(ii)
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All 21 questions on Conservation laws and particle equations, as a list
- June 2025, Unit 4, Q14(a)(ii) (2 marks): Explain how the law of conservation of baryon number and the law of conservation of charge are obeyed in this reaction. (2)
- June 2025, Unit 4, Q14(c) (3 marks): The photograph shows tracks produced by particles in a particle detector when a K – collided with a stationary proton. The tracks produced by the K + and Ω – ar
- January 2025, Unit 4, Q11 (3 marks): A nuclear reaction that occurs in the Sun is shown. p + p → p + n + e + + ve Two protons react to form a proton, a neutron, a positron, and an electron neutrino
- October 2024, Unit 4, Q18(b)(ii) (4 marks): Deduce whether the conservation of charge and the conservation of lepton number apply to this decay. (4)
- June 2024, Unit 4, Q14(b)(i) (5 marks): One type of leptoquark has charge +5e/3 Determine the baryon number and the lepton number for this leptoquark. Include the suggested quark and lepton in your wo
- January 2024, Unit 4, Q6 (1 mark): A pion can decay into two leptons. Which of the following decays is possible? A π – → e – + ve B π 0 → e – + ve C π 0 → e + + ve D π + → e + + ve
- January 2024, Unit 4, Q12 (3 marks): The diagram shows tracks produced by particles in a bubble chamber. P A charged particle interacts with a stationary proton at P. This produces two neutral part
- October 2023, Unit 4, Q21(b) (4 marks): The equation shows a pion decaying into a muon and an antineutrino. π– → μ– + νμ– Energy and momentum must be conserved in this decay. Explain two other conserv
- June 2023, Unit 4, Q9 (1 mark): Which of the following shows the β – decay of a nucleon? A n → p + β – + νe B n → p + β – + νe C p → n + β – + νe D p → n + β – + νe
- January 2023, Unit 4, Q11(b) (3 marks): Explain whether the following decay would be possible. You should consider conservation of charge and lepton number. – → e – + νe + ν – μ μ (3)
- October 2022, Unit 4, Q11(c) (4 marks): Charged pions usually decay into a muon (μ) and another particle X, as shown by the decay equation: π – → μ – + X A student suggests that X is an anti-neutrino
- June 2022, Unit 4, Q2 (1 mark): A proton collides with an antiproton. Which of the following could be produced by this collision? A π + + n B π − + p+ C π + + e− D π + + π −
- January 2022, Unit 4, Q16(b)(iii) (3 marks): Deduce the charge and baryon number for the omega particle. (3)
- January 2022, Unit 4, Q17(b) (2 marks): A muon (μ) can be produced by the decay shown in this nuclear equation. π− → μ− + ν− μ State the names of the two other particles involved. (2)
- October 2021, Unit 4, Q17(c) (3 marks): A student correctly suggests that this collision cannot lead to both particles being omega baryons, as this breaks a conservation law. Discuss the student’s sug
- October 2021, Unit 4, Q18(a) (2 marks): State two ways in which the diagram shows that an anti‑muon must also have a positive charge. (2)
- October 2021, Unit 4, Q18(e)(i) (1 mark): Write an equation for this decay process. (1)
- June 2021, Unit 4, Q3 (1 mark): Neutrinos can interact with protons to create neutrons. Which of the following equations shows this process? A νe + p → e+ + n B νe + p → e– + n C ν– e + p → e+
- January 2021, Unit 4, Q13(b) (6 marks): The equation shows the decay of an anti-neutron. 1 n¯ → −1 1 p¯ + 1 0 e¯ + νe 0 Explain how this equation shows that the decay obeys three conservation laws. (6
- October 2020, Unit 4, Q2 (1 mark): A student writes the following equation for the decay of a neutron. n → p + e– + νe Which of the following conservation laws is violated by the equation he has
- January 2020, Unit 4, Q1 (1 mark): A neutron can decay to produce a proton. Which of the following equations correctly shows neutron decay? A n o p + e+ + ve B n o p + e+ + ve C n o p + e– + ve D
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