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23. Nuclear physics
A section of Physics, 9702
Listing 10 of 119 questions
State what is meant by nuclear binding energy. The variation with nucleon number A of the binding energy per nucleon BE is shown in . BE A When uranium-235 (235 92U) absorbs a slow-moving neutron, one possible nuclear reaction is 92U + 1 0n 42Mo + 139 57La + 21 0n + 7 0 –1β + energy. State the name of this type of nuclear reaction. On , mark the position of 1. the uranium-235 nucleus (label this position U), 2. the molybdenum-95 (95 42Mo) nucleus (label this position Mo), 3. the lanthanum-139 (139 57La) nucleus (label this position La). The masses of some particles and nuclei are given in . mass / u β-particle neutron proton uranium-235 molybdenum-95 lanthanum-139 5.5 × 10–4 1.009 1.007 235.123 94.945 138.955 Calculate, for this reaction, 1. the change, in u, of the rest mass, change in mass = u 2. the energy released, in MeV, to three significant figures. energy = MeV
9702_w13_qp_42
THEORY
2013
Paper 4, Variant 2
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One likely means by which nuclear fusion may be achieved on a practical scale is the D-T reaction. State what is meant by nuclear fusion. In the D-T reaction, a deuterium (2 1H) nucleus fuses with a tritium (3 1H) nucleus to form a helium-4 (4 2He) nucleus. The nuclear equation for the reaction is 1H + 3 1H 2He + 1 0n + energy Some data for this reaction are given in . mass / u deuterium (2 1H) tritium (3 1H) helium-4 (4 2He) neutron (1 0n) 2.01356 3.01551 4.00151 1.00867 Calculate the energy, in MeV, equivalent to 1.00 u. Explain your working. energy = MeV Use data from and your answer in to determine the energy released in this D-T reaction. energy = MeV Suggest why, for the D-T reaction to take place, the temperature of the deuterium and the tritium must be high.
9702_w14_qp_41
THEORY
2014
Paper 4, Variant 1
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One likely means by which nuclear fusion may be achieved on a practical scale is the D-T reaction. State what is meant by nuclear fusion. In the D-T reaction, a deuterium (2 1H) nucleus fuses with a tritium (3 1H) nucleus to form a helium-4 (4 2He) nucleus. The nuclear equation for the reaction is 1H + 3 1H 2He + 1 0n + energy Some data for this reaction are given in . mass / u deuterium (2 1H) tritium (3 1H) helium-4 (4 2He) neutron (1 0n) 2.01356 3.01551 4.00151 1.00867 Calculate the energy, in MeV, equivalent to 1.00 u. Explain your working. energy = MeV Use data from and your answer in to determine the energy released in this D-T reaction. energy = MeV Suggest why, for the D-T reaction to take place, the temperature of the deuterium and the tritium must be high.
9702_w14_qp_42
THEORY
2014
Paper 4, Variant 2
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State what is meant by the binding energy of a nucleus. Data for two isotopes of uranium are given in . isotope binding energy per nucleon / MeV binding energy / MeV uranium-235 uranium-238 7.59 State what is meant by isotopes. Complete . Uranium-235 has a half-life of 7.1 × 108 years. Show that the decay constant λ of uranium-235 is 3.1 × 10−17 s−1. A sample of uranium-235 has an activity of 5.0 × 103 Bq. Calculate the mass of the sample. mass = g
9702_w15_qp_43
THEORY
2015
Paper 4, Variant 3
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Phosphorus-30 (30 15P) was the first artificial radioactive nuclide to be produced in a laboratory. This was achieved by bombarding aluminium-27 (27 13Al) with α-particles. A partial nuclear equation to represent this reaction is 13Al + α → 30 15P + Φ State the full nuclear notation for the α-particle, the particle represented by the symbol Φ. Data for the rest masses of the particles in the reaction are given in . particle mass / u 13Al α 15P Φ 26.98153 4.00260 29.97830 1.00867 Calculate, for this reaction, the change in the total rest mass of the particles, mass change = u the energy, in joule, equivalent to the mass change calculated in . energy = J With reference to your answer in , comment on the energy of the α-particle such that the reaction can take place.
9702_w16_qp_42
THEORY
2016
Paper 4, Variant 2
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Explain what is meant by the binding energy of a nucleus. The following nuclear reaction takes place: 92 U + 1 0 n 55 Cs + 90 x Rb + y1 0 n Determine the values of x and y. x = y = State the name of this type of nuclear reaction. Compare the binding energy per nucleon of uranium-235 with the binding energy per nucleon of caesium-144. Yttrium-90 decays into zirconium-90, a stable isotope. A sample initially consists of pure yttrium-90. Calculate the time, in days, when the ratio of the number of yttrium-90 nuclei to the number of zirconium-90 nuclei would be 2.0. The half-life of yttrium-90 is 2.7 days. time = days
9702_m20_qp_42
THEORY
2020
Paper 4, Variant 2
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State what is meant by the binding energy of a nucleus. A nucleus of uranium‑235 absorbs a neutron and becomes unstable. It then undergoes a fission reaction. One possible reaction is 92U + 1 0n 54Xe + 90 38Sr + neutrons. Determine the number of neutrons produced in this fission reaction. number = Data for the binding energies per nucleon for this fission reaction are given in Table 8.1. Table 8.1 isotope binding energy per nucleon / MeV uranium‑235 7.59 xenon‑142 8.37 strontium‑90 8.72 Calculate the energy released, in MeV, from the fission of one nucleus of uranium‑235. energy = MeV The isotope xenon‑142 is unstable. The isotope xenon‑132 is stable. Suggest a reason why xenon‑142 is unstable. Xenon‑142 decays into the isotope caesium‑142. A sample initially contains only nuclei of xenon‑142. After a time equal to 6.0 s, the ratio number of decayed nuclei of xenon‑142 number of undecayed nuclei of xenon‑142 is equal to 31. Calculate the half‑life of xenon‑142. Show your working. half‑life = s
9702_m24_qp_42
THEORY
2024
Paper 4, Variant 2
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The radioactive decay of some nuclei gives rise to the emission of α-particles. State what is meant by an α-particle, two properties of α-particles. 1. 2. One possible nuclear reaction involves the bombardment of a stationary nitrogen-14 nucleus by an α-particle to form oxygen-17 and another particle. Complete the nuclear equation for this reaction. 7 N + α 8 O + The total mass-energy of the nitrogen-14 nucleus and the α-particle is less than that of the particles resulting from the reaction. This mass-energy difference is 1.1 MeV. 1. Suggest how it is possible for mass-energy to be conserved in this reaction. 2. Calculate the speed of an α-particle having kinetic energy of 1.1 MeV. speed = m s–1
9702_s10_qp_22
THEORY
2010
Paper 2, Variant 2
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Questions Discovered
119