5.2.3. Radioactive decay
A subsection of Physics, 5054, through 5. Nuclear physics
Listing 10 of 23 questions
Two neutral atoms are atoms of different isotopes of the same element. State one similarity in the structures of these two atoms, one difference between the structures of these two atoms. The isotope plutonium-239 decays by the emission of an alpha-particle (symbol α) to an isotope of uranium (symbol U). The half-life for this decay is 2.4 × 104 years. Complete the equation for this decay. 94Pu U + α The count rate measured due to a pure sample of plutonium-239 is 6400 counts / second. Calculate the count rate after a period of 1.2 × 105 years has elapsed. count rate = shows an alpha-particle entering a uniform magnetic field. alpha-particle magnetic field out of page 1. On , draw the path of the alpha-particle in the magnetic field. 2. Explain why the alpha-particle follows the path you drew in 1. In a nuclear reactor at a power station, plutonium-239 is made to undergo nuclear fission. State what is meant by nuclear fission. State what happens to a plutonium-239 nucleus in the nuclear reactor to cause fission. State one advantage of generating electricity in a nuclear power station rather than using 1. an oil-fired power station, 2. an array of wind turbines.
5054_w18_qp_21
THEORY
2018
Paper 2, Variant 1
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The isotope thorium‑230 (230 90Th) decays by alpha particle (α‑particle) emission. Describe the composition of an α‑particle. State the name of the particle that is identical in composition to an α‑particle. The α‑particle decay of thorium‑230 produces an isotope of radium. Deduce: the number of neutrons in a neutral atom of this isotope of radium number of neutrons = the number of electrons in a neutral atom of this isotope of radium. number of electrons = The half‑life of thorium‑230 is 75 000 years. A radioactive sample contains 7.2 × 1016 thorium‑230 atoms. Determine the time it takes for the number of thorium‑230 atoms to decrease to 9.0 × 1015. time = years When it decays, thorium‑230 also emits gamma radiation (γ‑radiation). shows a narrow beam of γ‑radiation passing into an electric field. + + + + + + + + – – – – – – – – electric field direction beam of γ-radiation On , sketch the path of the γ‑radiation in the electric field. shows the electric field replaced with a magnetic field that is directed into the page. magnetic field into the page beam of γ-radiation On , sketch the path of the γ‑radiation in the magnetic field.
5054_w24_qp_22
THEORY
2024
Paper 2, Variant 2
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Questions Discovered
23