5.2.3. Radioactive decay
A subsection of Physics, 0625, through 5. Nuclear physics
Listing 10 of 133 questions
represents all the particles in a lithium atom. proton neutron electron Key (not to scale) State the proton number (atomic number) of the lithium atom in . Determine the nucleon number (mass number) of the lithium atom in . nucleon number = Describe how a lithium atom changes to form a positive ion. The half-life of iodine-131 is 8 days. A sample contains 80 mg of iodine-131. Calculate the time taken to decay until 10 mg of iodine-131 remain in the sample. time taken = days
0625_w23_qp_33
THEORY
2023
Paper 3, Variant 3
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Many household smoke alarms contain a sample of the radioactive isotope americium-241 (Am). Americium-241 is the isotope of the element americium that has the nucleon number (mass number) 241. State how the composition of a nucleus of americium-241 differs from that of a nucleus of americium-242. An atom of a different element has a nucleon number of 241. State two differences between the composition of a nucleus of this atom and a nucleus of americium-241. Americium-241 decays to an isotope of neptunium (Np) by alpha-particle (α-particle) emission. Complete the equation for this decay. Am 93Np + α One reason for using an isotope that emits α-particles in a smoke detector is that α-particles are more strongly ionising than beta-particles (β-particles). Explain why α-particles are more strongly ionising than β-particles. The isotope of neptunium produced by americium-241 is also radioactive. The decay of this isotope of neptunium produces an isotope of protactinium which decays by β-emission. β-particles are more penetrating than α-particles. The half-life of neptunium is longer than two million years. Using this information, explain the advantage of this long half-life for the use and safe disposal of a household smoke alarm.
0625_w23_qp_41
THEORY
2023
Paper 4, Variant 1
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Name three types of nuclear emission from radioactive sources. State the type of nuclear emission which has a relative charge of +2. State the type of nuclear emission which is part of the electromagnetic spectrum. The isotope technetium-99m decays to technetium-99. The half-life of technetium-99m is 6 hours. Determine the fraction of technetium-99m remaining in a sample after 18 hours. fraction remaining = The nuclide notation for technetium-99 is: 43Tc Complete the table below to show the number of each type of particle in a neutral atom of technetium-99. type of particle number electron neutron proton
0625_w24_qp_32
THEORY
2024
Paper 3, Variant 2
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Questions Discovered
133