Science 10 Radioactivity Review v3

Class: Date: Science 10 Radioactivity Review v3 Modified True/False Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true. 1. An atom s atomic number can never be greater than its mass number. 2. Different isotopes of a particular element have the same mass number but different atomic numbers. 3. The only type of radioactive decay that will produce daughter nuclei with different mass numbers is alpha decay. 4. Because alpha particles are the biggest, heaviest, and most highly charged of the three common types of radiation emitted during radioactive decay, they are also the most penetrating. 5. The daughter nucleus produced following gamma decay is the same element with the same atomic number and the same mass number as the parent nucleus. 6. Alpha decay will produce a daughter nucleus with more protons and beta decay will produce a daughter nucleus with fewer protons than the parent nucleus has. 7. The half-life of a given radioisotope can be altered by intense heat, pressure, or other physical means. 8. We have determined the dates during which dinosaurs lived on Earth by using radiocarbon dating. 9. The process of nuclear fission is much easier to initiate than nuclear fusion. 10. Nuclear reactors producing electrical energy take advantage of a controlled fusion chain reaction to produce heat and boil water that drives a steam turbine. Multiple Choice Identify the choice that best completes the statement or answers the question. 11. Which of the following emissions is not part of the electromagnetic spectrum? a. X-radiation c. beta radiation b. gamma radiation d. ultraviolet radiation 1

12. Which of the following correctly compares gamma rays to microwaves? a. Gamma rays have a shorter wavelength, a higher frequency, and carry less energy than microwaves. b. Gamma rays have a shorter wavelength, a higher frequency, and carry more energy than microwaves. c. Gamma rays have a longer wavelength, a lower frequency, and carry less energy than microwaves. d. Gamma rays have a shorter wavelength, a lower frequency, and carry more energy than microwaves. 13. Which of the following is true concerning the isotopes potassium-41 and potassium-39? a. Potassium-41 has two more protons than potassium-39. b. Potassium-41 has one more proton and one more electron than potassium-39. c. Potassium-41 has one more proton and one more neutron than potassium-39. d. Potassium-41 has two more neutrons than potassium-39. 14. Consider the following two isotopes of uranium: U and U Which of the following is true? a. One of the isotopes has 235 neutrons, and the other has 238 neutrons. b. One of the isotopes has 143 protons, and the other has 146 protons. c. One of the isotopes has 143 neutrons, and the other has 146 neutrons. d. One of the isotopes has a mass of 327, and the other has a mass of 330. 15. Which of the following is true concerning the elements in the periodic table? a. The neutron-to-proton ratio increases as the atomic numbers of the elements increase. b. The neutron-to-proton ratio decreases as the atomic numbers of the elements increase. c. The neutron-to-proton ratio is constant as the atomic numbers of the elements increase. d. The neutron-to-proton ratio changes randomly as the atomic numbers of the elements increase. 2

16. Which of the following applies to isotopes of an element? I. They have the same number of protons. II. They have the same number of neutrons. III. They have the same number of electrons. IV. They have the same atomic number. V. They have the same mass number. a. I., II., and III. only c. II., III., and IV. only b. I., III., and IV. only d. III., IV., and V. only 17. Which of the following is correct concerning atomic number, mass number, and neutron number for any nucleus? I. atomic number = mass number - neutron number II. mass number = atomic number - neutron number III. neutron number = mass number + atomic number IV. atomic number = mass number + neutron number V. mass number = atomic number + neutron number VI. neutron number = mass number - atomic number a. II., IV., and VI. only c. I., V., and VI. only b. II., III., and IV. only d. III., IV., and V. only 18. Using the below symbols, which of the following represents an alpha particle? a. symbol A c. symbol C b. symbol B d. symbol D 3

19. After a radioactive nucleus has decayed via alpha emission, the daughter nucleus has: a. an atomic number decreased by four, and a mass number decreased by two b. both a mass number and an atomic number decreased by two c. a mass number that is unchanged, and an atomic number increased by one d. a mass number decreased by four, and an atomic number decreased by two 20. After a radioactive nucleus has decayed via beta emission, the daughter nucleus has: a. an atomic number decreased by four, and a mass number decreased by two b. both a mass number and an atomic number decreased by two c. a mass number that is unchanged, and an atomic number increased by one d. a mass number decreased by four, and an atomic number decreased by two 21. Which of the following nuclear decay processes would form a daughter nucleus with an atomic number larger than the parent nucleus? a. α-decay c. γ-decay b. β-decay d. λ-decay 22. Considering the fact that the mass of a proton is approximately 1840 times the mass of an electron, which of the following is true? a. A beta particle is more than 7000 times the mass of an alpha particle. b. An alpha particle is almost 4000 times the mass of a beta particle. c. A beta particle is almost 4000 times the mass of an alpha particle. d. An alpha particle is more than 7000 times the mass of a beta particle. 23. The alpha decay of radon-222 will yield which of the following? a. polonium-218 c. astatine-222 b. francium-222 d. bismuth-220 24. What nucleus will be formed when Po first undergoes alpha decay and then the daughter nucleus formed from that decay undergoes beta decay? a. Tl c. Pb b. Bi d. At 25. If the daughter nucleus formed as a result of alpha decay is isotope of which element? a. thallium c. gold b. mercury d. lead Ir then the parent nucleus was an 4

26. Consider the below illustration representing a nuclear decay event: Which two of the following statements about the nature of the daughter nucleus are true? I. The mass is the same as the parent nucleus s mass. II. The mass is less than the parent nucleus s mass. III. The atomic number is lower than the parent nucleus s atomic number. IV. The atomic number is higher than the parent nucleus s atomic number. a. I. and III. c. II. and III. b. I. and IV. d. II. and IV. 27. If an isotope of iodine decays to an isotope of xenon, the type of decay must have been: a. fission c. alpha b. gamma d. beta 28. If nickel-60 undergoes gamma decay, the nucleus produced will be: a. nickel-60 c. copper-60 b. iron-56 d. iron-58 29. How would you describe the penetrating power of a beta particle? a. more penetrating than both alpha and gamma radiation b. less penetrating than both alpha and beta radiation c. more penetrating than gamma, but less penetrating than alpha radiation d. less penetrating than gamma, but more penetrating than alpha radiation 5

30. Which of the following correctly lists the types of emissions from slowest to fastest? Slowest Fastest a. α β γ b. α γ β c. β α γ d. γ β α a. a b. b c. c d. d 31. Which of the following symbols completes the decay equation below? Fr At +? a. β c. α b. γ d. n 32. Which of the following symbols completes the decay equation below? Au Hg +? a. β c. α b. γ d. n 33. If a radioactive sample of rutherfordium-257 undergoes gamma decay, which of the following will be formed after the release of the gamma radiation? a. Db c. Rf b. Lr d. No 34. Which of the following decay products will be repelled by a positively charged surface? a. an alpha particle c. a gamma ray b. a beta particle d. a neutron 35. Which of the following will have the greatest amount of charge relative to its mass, that is, the greatest charge-to-mass ratio? a. an alpha particle c. a neutron b. a beta particle d. a gamma ray 6

36. Which of the following types of decay will produce daughter nuclei with a different atomic number and mass number than the parent nucleus s atomic number and mass number? I. alpha decay II. beta decay III. gamma decay a. I. and II. only c. II. and III. only b. I. and III. only d. I., II., and III. 37. Which of the following represents the process whereby a beta particle is produced in the nucleus? a. He 2 p + 2 n c. e + e 2 γ b. p + e n d. n p + e 38. The half-life of plutonium-242 is about 400 000 years. How long would it take for a 10.0 g sample of this radioisotope to decay to 1.25 g? a. 800 000 years c. 1 600 000 years b. 1 200 000 years d. 2 000 000 years 39. The half-life of zinc-71 is 2.4 min. If you began with 50.0 g of this substance, what mass remains after 9.6 min? a. 3.12 g c. 12.5 g b. 6.25 g d. 25.0 g 40. What percentage of carbon-14 will be left in a fossilized organism if the organism died approximately 29 000 years ago? a. 1.56 percent c. 6.25 percent b. 3.12 percent d. 12.5 percent 41. A geologist attempts to date a sample of volcanic rock using potassium-40 as a radioactive clock. She finds that the ratio of argon-40 to potassium-40 in the rock is 7 to 1. She will estimate the age of the rock to be approximately: a. 1.3 billion years c. 3.9 billion years b. 2.6 billion years d. 5.2 billion years 42. Which of the following isotope pairs is likely to have a daughter-to-parent ratio of 3 to 1 after approximately 1.5 billion years? Parent Daughter a. thorium-235 lead-206 b. rubidium-87 strontium-87 c. potassium-40 argon-40 d. uranium-235 lead-207 a. a b. b c. c d. d 7

43. A bone found at a newly discovered ancient burial site is dated using carbon-14. A sample of the bone is found to contain approximately 12.5 percent of the carbon-14 present in a living sample. The age of the fossil is approximately: a. 18 000 years c. 30 000 years b. 24 000 years d. 36 000 years Use the following information to answer the next three questions. On April 26, 1986, an explosion at the nuclear power plant at Chernobyl in Ukraine released the greatest quantity of radioactive material ever associated with an industrial accident. One of the principal radioisotopes released was iodine-131, which has a half-life of 8 days. Iodine-131 decays via beta emission. 44. The daughter nucleus resulting from the decay of iodine-131 is: a. antimony-127 c. tellurium-129 b. indium-128 d. xenon-131 45. What would the daughter-to-parent ratio be for this isotope pair 32 days after the iodine-131 was released into the environment? a. 3 to 1 c. 15 to 1 b. 7 to 1 d. 31 to 1 46. The official account of the Chernobyl accident estimates the total amount of iodine-131 released to be between 80 and 400 g. If measurements taken 40 days after the accident indicated that a total of 10 g of iodine-131 remained, what mass of this radioisotope was originally released? a. 80 g c. 160 g b. 120 g d. 320 g 8

Use the following decay curve for strontium-90 to answer the next two questions. 47. The half-life of strontium-90 is approximately: a. 15 years c. 50 years b. 30 years d. 60 years 48. What mass of strontium-90 will exist in 150 years if you began with 100.0 g today? a. 25.0 g c. 6.25 g b. 12.5 g d. 3.12 g 9

Use the following information and graph to answer the next three questions. A hypothetical radioisotope decays via beta emission to a stable isotope in one step. The decay curve for this is shown below. 49. The half-life of this radioisotope is approximately: a. 5 days c. 15 days b. 10 days d. 20 days 50. What mass of the parent isotope remains after 25 days? a. 6.25 g c. 25.0 g b. 12.5 g d. 50.0 g 51. How much time has elapsed since the parent isotope s original mass of 200 g began decaying if 187.5 g of the daughter isotope have been produced? a. 10 days c. 25 days b. 20 days d. 30 days 52. Carbon-14 is radioactive, while its daughter nucleus nitrogen-14 is stable. This fact suggests that the instability of the carbon-14 nucleus may result from: a. too many protons relative to neutrons in the nucleus b. too much mass in the nucleus c. too many electrons relative to protons in the nucleus d. too many neutrons relative to protons in the nucleus 10

53. The half-life of magnesium-28 is 21 hours. If a 40 g sample of this radioisotope began decaying now, how many hours would pass before only 2.5 g remained? a. 63 hours c. 105 hours b. 84 hours d. 126 hours 54. Consider the following nuclear equation: He + N? + H The missing element is: a. oxygen c. neon b. fluorine d. sodium 55. Which of the following are correct statements about nuclear fission? I. Two small nuclei fuse to form a single larger nucleus. II. Mass is converted into energy. III. Nuclear power plants employ the process to generate energy. IV. The process occurs in the Sun and in hydrogen bombs. a. I., II., and III. only c. II. and III. only b. I. and IV. only d. I., II., III., and IV. 56. To initiate a uranium fission reaction in a nuclear reactor, uranium-235 nuclei must absorb: a. alpha particles c. gamma rays b. beta particles d. neutrons 57. Assuming the masses of the starting materials are the same, approximately how much more energy is available from a nuclear fission reaction than from the most energetic chemical reaction? a. approximately 1000 times more energy b. approximately 100 000 times more energy c. approximately 1 000 000 times more energy d. approximately 1 000 000 000 times more energy 58. When uranium-235 undergoes fission, a number of possible fission products can result. The following represents one possible fission result: n + U Kr +? + 3 n + energy Which of the following represents the missing daughter nucleus? a. Cs c. Ba b. Mo d. Nd 11

59. Which of the following represent the energy transformations occurring in a typical nuclear reactor? a. electrical mechanical thermal nuclear b. nuclear thermal mechanical electrical c. nuclear mechanical thermal electrical d. mechanical thermal electrical nuclear 60. Which of the following represents a nuclear fission reaction? a. U + n Kr + Ba + 3 n + energy b. H + H He + n + energy c. U Th + He + energy d. Fe + e Mn + energy 61. Which of the following correctly describe nuclear fusion? I. It is easier to initiate than nuclear fission. II. It occurs in the core of the sun. III. It involves the splitting of a large nucleus into smaller nuclei. IV. It releases much more energy than nuclear fission. a. I. and II. only c. I., II., and III. only b. II., III., and IV. only d. II. and IV. only 62. Which of the following correctly compare nuclear fission to nuclear fusion? I. Nuclear fission is easier to initiate than nuclear fusion. II. Nuclear fission releases much more energy than nuclear fusion. III. Nuclear fission is not employed in bombs, but nuclear fusion is. IV. Nuclear fission reactors are the only type of reactors operating at present. a. I. and II. only c. I. and IV. only b. I. and III. only d. I., II., and IV. only 63. Which of the following represents a nuclear fusion reaction? a. U + n Kr + Ba + 3 n + energy b. H + H He + n + energy c. U Th + He + energy d. Fe + e Mn + energy 12

64. Consider the following nuclear equation: He +? He + 2 H Which of the following represents the missing particle? a. H c. H b. He d. He 65. Which of the following correctly compares nuclear fusion to nuclear fission? a. Nuclear fusion is much easier to initiate and produces more energy than nuclear fission. b. Nuclear fusion is much more difficult to initiate and produces more energy than nuclear fission. c. Nuclear fusion is much easier to initiate and produces less energy than nuclear fission. d. Nuclear fusion is much more difficult to initiate and produces less energy than nuclear fission. 66. The majority of the energy released from a hydrogen bomb results from: a. a controlled fission chain reaction c. a controlled fusion chain reaction b. an uncontrolled fission chain reaction d. an uncontrolled fusion chain reaction 67. Which of the following is a concern even when a nuclear reactor is operating safely? a. Some nuclear waste material has a long half-life. b. The world s supply of uranium is very low. c. Nuclear reactors generate a large amount of greenhouse gases. d. Nuclear energy does not produce a lot of electricity. 68. Assuming the masses of the starting materials are the same, approximately how much more energy is available from a nuclear fusion reaction than from the most energetic chemical reaction? a. approximately one thousand times more energy b. approximately one million times more energy c. approximately one-hundred million times more energy d. approximately one billion times more energy 69. A major obstacle associated with the development of fusion reactors for commercial energy production is: a. the worldwide shortage of available hydrogen for fuel b. the fact that the energy available from fusion reactors is much less than that from fission reactors c. the huge temperatures required to initiate and maintain nuclear fusion d. that fusion reactors will generate much more radioactive waste than fission reactors generate 13

70. The bombs dropped on Hiroshima and Nagasaki in early August 1945 were examples of: a. controlled fission chain reactions c. controlled fusion chain reactions b. uncontrolled fission chain reactions d. uncontrolled fusion chain reactions Matching Match the atomic symbol with the correct description below. Each symbol may be used only once. a. U d. Rf b. Xe e. Pb c. Ba 71. This will be produced in addition to krypton-92 and 3 neutrons when uranium-235 absorbs a neutron and undergoes nuclear fission. 72. This stable isotope with 114 neutrons is the final product in the decay series of uranium-238. 73. This nucleus with 153 neutrons will be produced when rutherfordium-257 undergoes gamma decay. 74. This non-fissionable nucleus contains 146 neutrons. 75. This isotope containing 77 neutrons is produced following the beta decay of iodine-131. Match the description of the nuclear changes with the correct type of decay. Each type of decay may be used more than once. a. alpha decay c. gamma decay b. beta decay 76. A nucleus releases energy in the form of electromagnetic radiation. 77. The positive charge on the daughter nucleus is greater than that of the parent nucleus. 78. The mass of the daughter nucleus is less than that of the parent nucleus. 79. A high-speed negative particle is ejected from the nucleus. 80. Neither the mass number nor the atomic number of the nucleus changes following this decay. 81. A particle composed of two of each of the subatomic particles contributing mass to the atom is ejected from the nucleus. 14

Match each description regarding the amount of daughter and parent nuclei present to the correct parent isotope and half-life. Each description may be used only once. a. After 11 460 years, 25 percent of the parent isotope remains. b. After one month, approximately 87.5 percent of the parent isotope has decayed. c. Twice as much daughter isotope exists as parent isotope after 1.4 billion years. d. After 650 million years, approximately 25 percent of the parent isotope has decayed. e. Approximately 3 percent of the parent isotope remains after 140 years. 82. uranium-235 / 710 million years 83. strontium-90 / 28 years 84. potassium-40 / 1.3 billion years 85. carbon-14 / 5730 years 86. iodine-131 / 8 days When uranium-235 absorbs a neutron, there are many possible fission products. Match the missing fission product to the correct nuclear equation below. Each fission product may be used only once. a. Ge c. Kr b. Rb d. Mo 87. U + n? + Ba + 3 n 88. U + n? + In + 3 n 89. U + n? + Cs + 3 n 90. U + n? + Nd + 3 n Short Answer 91. Describe the complete make-up of the atom represented by the following symbol: Ir 92. Describe the following types of radioactive decay and the nuclear changes taking place as each occurs. a) alpha decay b) beta decay c) gamma decay 15

93. One of the steps in the decay series of uranium-238 is the alpha decay of radon-222. Write the complete nuclear equation below representing the alpha decay of radon-222. 94. Write the complete nuclear equation for the beta decay of mercury-201. 95. Potassium-40 has a half-life of 1.3 billion years and decays to stable argon-40. Use this information to describe how the age of a rock sample possessing 15 g of argon-40 and 5 g of potassium-40 can be dated. 96. When 1.0 kg of uranium-235 undergoes nuclear fission in a reactor, the sum of the masses of all the fission products is slightly less than 1.0 kg. Explain what has happened to the lost mass during the fission process, and write the equation that applies. 97. Below, state two ways in which nuclear fission and nuclear fusion are similar and two ways in which they are different. 98. Convert the following written description of a nuclear fission event into a balanced nuclear equation: An atom of uranium-235 absorbs a neutron and undergoes fission, producing nuclei of strontium-94 and xenon-140, 2 neutrons, and energy. 99. Convert the following written description of a nuclear fusion event into a balanced nuclear equation: A nucleus of hydrogen-2 (deuterium) and a nucleus of hydrogen-3 (tritium) undergo fusion producing helium-4, 1 neutron, and energy. 100. Physicists refer to a hydrogen bomb as a thermonuclear device. This is because the fusion of hydrogen in the bomb requires a fission detonation to occur first. Explain why this initial fission event is necessary. Problem 101. Use your periodic table to fill in the blank spaces in the following table. Isotope Name Proton Number Neutron Number Mass Number Atomic Notation technetium-99 115 192 W 101 256 103 153 99 Es 16

102. Several subatomic particles involved in nuclear reactions can be represented with two symbols, each meaning the same thing. Complete the following table by writing the two symbols that could represent each of the particles. Particle Name Symbol #1 Symbol #2 alpha particle beta particle proton 103. Complete the following table by filling in the blank spaces. Name of Particle/Ray gamma ray beta particle Symbol Charge Relative Mass p 0 1 Nature of Particle/Ray helium nucleus emitted from unstable parent nucleus nuclear particle with 1+ charge 104. Write nuclear equations for the following examples of radioactive decay: a) alpha decay of neodymium-144 b) gamma decay of californium-254 c) beta decay of neptunium-239 105. When a radioisotope undergoes beta decay, all three subatomic particles in the atom are involved in the process. As an example, write the nuclear equation representing the beta decay of carbon-14 below and explain the role that each of the three subatomic particles plays in the process. 106. Probably the most widely used isotopes for dating rock are the potassium-40/argon-40 pair. The half-life of K-40 is 1.3 billion years, and the ratio of Ar-40 to K-40 in a rock sample allows the age of the rock to be estimated. If a 3.9-billion-year-old rock sample initially contained 120 g of potassium-40, what mass of K-40 and Ar-40 would exist in the sample now? 107. Strontium-90 undergoes beta decay and has a half-life of 28 years. a) Write the nuclear equation for the beta decay of strontium-90. b) Determine the amount of strontium-90 that would remain 112 years from now if you began with 80 g today. c) What will the daughter-to-parent mass ratio be after 112 years? 17

108. Iodine-131 has a half-life of 8 days. Assume you began with 10.0 g of iodine-131 today. On the following set of axes, sketch a decay curve for iodine-131 representing a 56-day time period. Label clearly on the graph the amount of iodine-131 remaining after 40 days. 109. An ancient burial site has been discovered, and radiocarbon dating is being employed to date the human remains found in the graves. If the amount of carbon-14 remaining in one of the bones found at the site is determined to be (1.56 percent) of the amount present in living bone material, approximately how long ago did this individual die? 110. Large quantities of energy can be produced by the fusion of two light nuclei. This occurs in stars such as our Sun, which gives off vast amounts of energy from the fusion of protons to form helium. The series of nuclear fusion reactions are given below, each with a component missing. Complete the following nuclear equations by adding the missing component. (Note: The symbol e represents a particle called a positron, which has a mass equal to an electron but has a 1+ charge.) a) H + H? + e b) H + H? c) He +? He + 2 H d)? + H He + e 18