Physics: Standard Level
Nuclear and quantum physics — Theme E
- 1.
A nucleus of uranium-238 (₉₂²³⁸U) decays by emitting an alpha particle. Write the nuclide notation of the resulting daughter nucleus.
[3 marks] · no calculator - 2.
Marking analysis: A learner attempts the following task: “A nucleus of uranium-238 (₉₂²³⁸U) decays by emitting an alpha particle. Write the nuclide notation of the resulting daughter nucleus.” Their response addresses only this point: “States that an alpha particle removes mass number 4 and atomic number 2.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 3.
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] - 4.
Marking analysis: A learner attempts the following task: “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.” Their response addresses only this point: “Identifies that 20 days is four half-lives.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] - 5.
Distinguish between alpha, beta and gamma radiation in terms of their penetrating power through materials.
[3 marks] · no calculator - 6.
Marking analysis: A learner attempts the following task: “Distinguish between alpha, beta and gamma radiation in terms of their penetrating power through materials.” Their response addresses only this point: “States that alpha radiation is stopped by a few centimetres of air or a sheet of paper (least penetrating).” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[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.
Marking analysis: A learner attempts the following task: “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.” Their response addresses only this point: “States that the atom has a small, dense, positively charged nucleus at its centre, containing protons and neutrons.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 9.
Calculate the energy of a photon of light with wavelength 500 nm. Use h = 6.63 × 10⁻³⁴ J s and c = 3.00 × 10⁸ m s⁻¹.
[3 marks] - 10.
Marking analysis: A learner attempts the following task: “Calculate the energy of a photon of light with wavelength 500 nm. Use h = 6.63 × 10⁻³⁴ J s and c = 3.00 × 10⁸ m s⁻¹.” Their response addresses only this point: “Uses E = hc/λ.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] - 11.
Explain the photoelectric effect, and state why it provides evidence for the particle (photon) nature of light.
[4 marks] · no calculator - 12.
Marking analysis: A learner attempts the following task: “Explain the photoelectric effect, and state why it provides evidence for the particle (photon) nature of light.” Their response addresses only this point: “States that the photoelectric effect is the emission of electrons from a metal surface when light of sufficient frequency shines on it.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 13.
Distinguish between nuclear fission and nuclear fusion, and state one condition required for each to occur.
[3 marks] · no calculator - 14.
Marking analysis: A learner attempts the following task: “Distinguish between nuclear fission and nuclear fusion, and state one condition required for each to occur.” Their response addresses only this point: “States that fission is the splitting of a large, unstable nucleus into two smaller nuclei, usually triggered by neutron absorption.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 15.
Explain how the de Broglie hypothesis extends wave-particle duality to matter, and calculate the de Broglie wavelength of an electron moving at 2.0 × 10⁶ m s⁻¹. Use h = 6.63 × 10⁻³⁴ J s and the electron mass = 9.11 × 10⁻³¹ kg.
[4 marks] - 16.
Marking analysis: A learner attempts the following task: “Explain how the de Broglie hypothesis extends wave-particle duality to matter, and calculate the de Broglie wavelength of an electron moving at 2.0 × 10⁶ m s⁻¹. Use h = 6.63 × 10⁻³⁴ J s and the electron mass = 9.11 × 10⁻³¹ kg.” Their response addresses only this point: “States that de Broglie proposed that matter, like light, exhibits both particle and wave properties, with an associated wavelength.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] - 17.
Outline the evidence provided by atomic line emission spectra for the existence of discrete (quantised) electron energy levels within an atom.
[3 marks] · no calculator - 18.
Marking analysis: A learner attempts the following task: “Outline the evidence provided by atomic line emission spectra for the existence of discrete (quantised) electron energy levels within an atom.” Their response addresses only this point: “States that an excited atom emits light only at specific, discrete wavelengths (a line spectrum), rather than a continuous range of wavelengths.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 19.
A nucleus of nitrogen-14 undergoes a nuclear reaction, absorbing an alpha particle and emitting a proton, producing an isotope of oxygen. Write the balanced nuclear equation for this reaction.
[3 marks] · no calculator - 20.
Marking analysis: A learner attempts the following task: “A nucleus of nitrogen-14 undergoes a nuclear reaction, absorbing an alpha particle and emitting a proton, producing an isotope of oxygen. Write the balanced nuclear equation for this reaction.” Their response addresses only this point: “Writes the reactants: ₇¹⁴N + ₂⁴He.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 21.
A helium-4 nucleus has a mass of 4.001505 u. Its constituent 2 protons (1.00728 u each) and 2 neutrons (1.00867 u each) have a combined mass of 4.03190 u. Calculate the mass defect and the binding energy of the helium-4 nucleus. Use 1 u = 931.5 MeV/c².
[4 marks] - 22.
Marking analysis: A learner attempts the following task: “A helium-4 nucleus has a mass of 4.001505 u. Its constituent 2 protons (1.00728 u each) and 2 neutrons (1.00867 u each) have a combined mass of 4.03190 u. Calculate the mass defect and the binding energy of the helium-4 nucleus. Use 1 u = 931.5 MeV/c².” Their response addresses only this point: “Calculates the mass defect: Δm = 4.03190 − 4.001505 = 0.030395 u.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] - 23.
Cobalt-60 (₂₇⁶⁰Co) undergoes beta-minus decay. Write the balanced nuclear equation for this decay, identifying the emitted particle.
[3 marks] · no calculator - 24.
Marking analysis: A learner attempts the following task: “Cobalt-60 (₂₇⁶⁰Co) undergoes beta-minus decay. Write the balanced nuclear equation for this decay, identifying the emitted particle.” Their response addresses only this point: “States that in beta-minus decay, a neutron in the nucleus converts into a proton, emitting an electron (a beta particle).” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 25.
Explain what is meant by the random and spontaneous nature of radioactive decay, and state why it is impossible to predict when a specific individual nucleus will decay.
[3 marks] · no calculator - 26.
Marking analysis: A learner attempts the following task: “Explain what is meant by the random and spontaneous nature of radioactive decay, and state why it is impossible to predict when a specific individual nucleus will decay.” Their response addresses only this point: “States that radioactive decay is spontaneous: it is not affected by external conditions such as temperature, pressure or chemical state.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator - 27.
Sodium-22 (₁₁²²Na) decays by beta-plus (positron) emission. Write the balanced nuclear equation for this decay, and state what happens to the mass number and atomic number.
[4 marks] · no calculator - 28.
Marking analysis: A learner attempts the following task: “Sodium-22 (₁₁²²Na) decays by beta-plus (positron) emission. Write the balanced nuclear equation for this decay, and state what happens to the mass number and atomic number.” Their response addresses only this point: “States that in beta-plus decay, a proton in the nucleus converts into a neutron, emitting a positron.” Evaluate the response against the complete 4-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[4 marks] · no calculator - 29.
State one medical use of a radioactive isotope, and explain why gamma-emitting isotopes with short half-lives are generally preferred for use as internal medical tracers.
[3 marks] · no calculator - 30.
Marking analysis: A learner attempts the following task: “State one medical use of a radioactive isotope, and explain why gamma-emitting isotopes with short half-lives are generally preferred for use as internal medical tracers.” Their response addresses only this point: “States a valid use, e.g. as a tracer to monitor organ function, or in the treatment of cancerous tumours.” Evaluate the response against the complete 3-mark task. Identify what earns credit and state every additional requirement needed for full marks.
[3 marks] · no calculator