Nuclear Review Answer Key
1. D
2. B
3. C
4. E
5. A
6. F
7. D
8. B
9. F
10. A
11. G
12. E
13. C
14. C
15. A
16. C
17. C
18. B
19. C
20. C
21. C
22.D
23. A
24. D
25. C
26. D
27. D
28. B
29. B
30. C
31. A
32. C
33.B
34. B
35. B
36. B
37. A
38. D
39.B
40. B
41. C
42. A
43. C
44. D
45. B
46. D
47. A
48. A
49.A
50. C
51. D
52. A
53. C
54. A
55. D
56. A
57. A
58. D
59. C
60. A
61. B
62. C
63. D
64. 235 U 4He + 231 Th
92 2 90
65. 8 years
66. 14 days
67. 23 days/3.8 days =approximately 6 half-lives have passed.
73.9 g x (1/2)^6 = 1.2 g remaining.
68. 0.63 g
69. 8 days
70. 11,460 years ago
71. 2
72. 1
73. 16
74. 83
75. 92
76. Alpha particles are helium nuclei; they have 2 protons and 2 neutrons. Alpha particles have relatively low energy and are the least penetrating of the three types of ionizing radiation. Beta particles are fast moving electrons that are intermediate in energy and penetrating power. Gamma rays are electromagnetic radiation in the form of high-energy photons. Alpha particle emission reduces the atomic number of a radioisotope by 2, and the atomic mass number by 4. Beta particle emission increases the atomic number by 1 and does not change the atomic mass number. Gamma ray emission neither alters the atomic number nor the atomic mass number.
77. 32 days is the equivalent of 4 half-life periods. 1/16 of the original sample remains. 1/16 of 32 g is 2.0 g. There are 2 g remaining.
78. 1/8 of the sample remains which is the result of 3 half-lives. 3 half-lives = 252 days, so one half-life = 252/3 days. Therefore, half-life of Scandium-46 is 84 days.
79. In artificial transmutation, atoms of one element are bombarded in the lab with high energy particles to convert them into other elements. Example, Nitrogen-14 can be converted to fluorine-18. Ernest Rutherford in 1919 did this when he bombarded nitrogen gas with alpha particles to make the unstable isotope of fluorine-18.
80. Film badges are worn by workers and later developed. Dark patches on the film indicate radiation exposure. Geiger counters measure the ionization of gas in a tube with a voltage across it. When exposed to radiation, the gas becomes ionized by contact with charged particles such as beta particles. Geiger counters detect the radiation which can be alpha, beta or gamma as electric current that conducts through the ionized gas. Scintillation counters emit light when struck by ionizing radiation. The number of light flashes and their respective energies are recorded electronically. Scintillation counters can detect all types of ionizing radiation.