. A sample of radioactive carbon-4 decays into a stable isotope of nitrogen. As the carbon-4 decays, the rate at which the amount of nitrogen is produced A. decreases linearly with time. B. increases linearly with time. C. decreases exponentially with time. D. increases exponentially with time.. Either of the two following graphs is useful in predicting nuclear energy changes in fission and fusion processes. Y Y 0 0 X 0 0 X Which one of the following correctly identifies the quantities X and Y? X Y A. atomic number total binding energy B. mass number total binding energy C. atomic number average binding energy per nucleon D. mass number average binding energy per nucleon
. Which one of the following provides direct evidence for the existence of discrete energy levels in an atom? A. The continuous spectrum of the light emitted by a white-hot metal. B. The line emission spectrum of a gas at low pressure. C. The emission of gamma radiation from radioactive atoms. D. The ionization of gas atoms when bombarded by alpha particles. 4. A sample of material initially contains atoms of only one radioactive isotope. Which one of the following quantities is reduced to one half of its initial value during a time equal to the half-life of the radioactive isotope? A. Total mass of the sample B. Total number of atoms in the sample C. Total number of nuclei in the sample D. Activity of the radioactive isotope in the sample 5. K-capture is a process that occurs when a nucleus captures an electron from the innermost shell of electrons surrounding the nucleus. When K-capture occurs in iron-55 ( 55 6 nucleus. Which equation represents this change? 55 0 55 A. ( Fe) + e Mn 6 7 Fe), the nucleus is changed into a manganese (Mn) 55 56 B. ( Fe) + e Mn 6 7 55 0 55 C. ( Fe) + e Mn 6 5 55 56 D. ( Fe) + e Mn 6 5
6. Isotopes provide evidence for the existence of A. protons. B. electrons. C. nuclei. D. neutrons. 7. This question is about atomic and nuclear structure. In a nuclear model of the atom, most of the atom is regarded as empty space. A tiny nucleus is surrounded by a number of electrons. (a) Outline one piece of experimental evidence that supports this nuclear model of the atom................... () (b) Explain why the protons in a nucleus do not fly apart from each other.............
(c) In total, there are approximately 0 9 electrons in the atoms making up a person. (i) Estimate the electrostatic force of repulsion between two people standing 00 m apart as a result of these electrons. (4) Explain why two people standing 00 m apart would not feel the force that you have calculated in part (i). (Total marks) 8. This question is about nuclear binding energy. (a) (i) Define nucleon. Define nuclear binding energy of a nucleus. 4
The axes below show values of nucleon number A (horizontal axis) and average binding energy per nucleon E (vertical axis). (Binding energy is taken to be a positive quantity). E / MeV 9 8 7 6 5 4 0 0 5 50 75 00 5 50 75 00 5 50 A (b) Mark on the E axis above, the approximate position of 56 6 (i) the isotope Fe (label this F). the isotope H (label this H). 8 (iii) the isotope U (label this U). 9 (c) Using the grid in part (a), draw a graph to show the variation with nucleon number A of the average binding energy per nucleon E. 5
(d) Use the following data to deduce that the binding energy per nucleon of the isotope He is. MeV. nuclear mass of mass of proton mass of neutron He =.060 u =.0078 u =.00867 u............... () In the nuclear reaction H + H He + 0 n energy is released. (e) (i) State the name of this type of reaction. Use your graph in (c) to explain why energy is released in this reaction. (Total marks) 6
9. This question is about nuclear reactions. (a) (i) Distinguish between fission and radioactive decay. (4) A nucleus of uranium-5 ( 5 9 U ) may absorb a neutron and then undergo fission to produce 90 4 Xe 8 54 nuclei of strontium-90 ( Sr ) and xenon-4 ( ) and some neutrons. The strontium-90 and the xenon-4 nuclei both undergo radioactive decay with the emission of β particles. Write down the nuclear equation for this fission reaction. (iii) State the effect, if any, on the mass number (nucleon number) and on the atomic number (proton number) of a nucleus when the nucleus undergoes β decay. Mass number:... Atomic number:... 7
The uranium-5 nucleus is stationary at the time that the fission reaction occurs. In this fission reaction, 98 MeV of energy is released. Of this total energy, 0 MeV and 65 MeV are the kinetic energies of the strontium-90 and xenon-4 nuclei respectively. (b) (i) Calculate the magnitude of the momentum of the strontium-90 nucleus. (4) Explain why the magnitude of the momentum of the strontium-90 nucleus is not exactly equal in magnitude to that of the xenon-4 nucleus. On the diagram below, the circle represents the position of a uranium-5 nucleus before fission. The momentum of the strontium-90 nucleus after fission is represented by the arrow. strontium-90 (iii) On the diagram above, draw an arrow to represent the momentum of the xenon-4 nucleus after the fission. 8
(c) In a fission reactor for the generation of electrical energy, 5% of the total energy released in a fission reaction is converted into electrical energy. (i) Using the data in (b), calculate the electrical energy, in joules, produced as a result of nuclear fission of one nucleus. The specific heat capacity of water is 4. 0 J Kg K. Calculate the energy required to raise the temperature of 50 g of water from 0 C to its boiling point (00 C). () (iii) Using your answer to (c)(i), determine the mass of uranium-5 that must be fissioned in order to supply the amount of energy calculated in (c). The mass of a uranium-5 atom is.9 0 5 kg. (4) (Total 5 marks) 9
0. This question is about nuclear reactions. (a) Complete the table below, by placing a tick ( ) in the relevant columns, to show how an increase in each of the following properties affects the rate of decay of a sample of radioactive material. Property temperature of sample pressure on sample amount of sample Effect on rate of decay increase decrease stays the same Radium-6 ( 6 88 Ra) undergoes natural radioactive decay to disintegrate spontaneously with the emission of an alpha particle (α-particle) to form radon (Rn). The masses of the particles involved in the reaction are radium: radon: α-particle: 6.054 u.076 u 4.006 u (b) (i) Complete the nuclear reaction equation below for this reaction. 6 88............ Ra + Rn Calculate the energy released in the reaction. () 0
(c) The radium nucleus was stationary before the reaction. (i) Explain, in terms of the momentum of the particles, why the radon nucleus and the α-particle move off in opposite directions after the reaction. () The speed of the radon nucleus after the reaction is v R and that of the α-particle is v α v α. Show that the ratio is equal to 55.5. v R () (iii) Using the ratio given in above, deduce that the kinetic energy of the radon nucleus is much less than the kinetic energy of the α-particle. ()
(d) Not all of the energy of the reaction is released as kinetic energy of the α-particle and of the radon nucleus. Suggest one other form in which the energy is released.... Another type of nuclear reaction is a fusion reaction. This reaction is the main source of the Sun s radiant energy. (e) (i) State what is meant by a fusion reaction. () Explain why the temperature and pressure of the gases in the Sun s core must both be very high for it to produce its radiant energy. High temperature:............ High pressure:............ (5) (Total 5 marks)
. This question is about nuclear binding energy. (a) Define nuclear binding energy....... The axes below show values of nucleon number A (horizontal axis) and average binding energy per nucleon E (vertical axis). (Binding energy is taken to be a positive quantity). E / MeV 9 8 7 6 5 4 0 0 5 50 75 00 5 50 75 00 5 50 A (b) Mark on the E axis opposite, the approximate position of 56 (i) the isotope Fe (label this F). the isotope H (label this H). 6 8 (iii) the isotope U (label this U). 9
(c) Using the grid opposite, draw a graph to show the variation with nucleon number A of the average binding energy per nucleon E. (d) Use the following data to deduce that the binding energy per nucleon of the isotope He is. MeV. nuclear mass of mass of proton mass of neutron He =.060 u =.0078 u =.00867 u............... () In the nuclear reaction H + He + energy is released. H n 0 (e) (i) State the name of this type of reaction. Use your graph in (e) to explain why energy is released in this reaction. (Total marks) 4