Half Life and Nuclear Problems
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Transcript of Half Life and Nuclear Problems
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1. Which equation represents the radioactive decay
of 22688 Ra?
1) 22688 Ra - 22286 Rn +
42He
2) 22688 Ra - 22689 Ac +
01e
3) 22688 Ra - 22687 Fr +
0+1e
4) 22688 Ra - 22588 Ra +
10n
2. The chart below shows the spontaneous nuclear
decay of U-238 to Th-234 to Pa-234 to U-234.
What is the correct order of nuclear decay
modes for the change from U-238 to U-234?
1) decay, decay, decay2) decay, decay, decay3) decay, decay, decay4) decay, decay, decay
3. Which product of nuclear decay has mass but no
charge?
1) alpha particles 3) gamma rays
2) neutrons 4) beta positrons
4. In the equation:
23940 Th
234 91 Pa + X
The symbol X represents
1) 0+1e
2) 01e
3) 10n
4) 11H
5. In the equation:
23491 Pa
234 92U + X
The X represents a
1) helium nucleus 3) proton
2) beta particle 4) neutron
6. According to the equation:
X 20882 Pb +
42He
The nucleus correctly represented by X is
1) 20480 Hg
2) 21284 Po
3) 20480 Bi
4) 21284 Pb
7. In the equation:
23490 Th
23491 Pa + X
Which particle is represented by X?
1) 01e
2) 42He
3) 11H
4) 0+1e
8. In the equation:
226 88Ra
222 86Rn + X
X represents
1) a neutron 3) a beta particle
2) a proton 4) an alpha particle
9. Given the reaction:
23491 Pa X +
01e
When the equation is correctly balanced the
nucleus represented by X is
1) 23492 U
2) 23592 U
3) 23090 Th
4) 23290 Th
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10. Given the equation:
18 9F
18 8O + X
Which symbol, when substituted for X, correctly
balances the equation?
1) 11H
2) 10n
3) 01e
4) 0+1e
11. In the equation:
X 226 88Ra +
42He
The symbol X represents
1) 222 86Th
2) 230 90Th
3) 222 86Rn
4) 230 90Rn
12. A neutron has approximately the same mass as
1) an alpha particle 3) an electron
2) a beta particle 4) a proton
13. What is the half-life of sodium-25 if 1.00 gram
of a 16.00-gram sample of sodium-25 remains
unchanged after 237 seconds?
1) 47.4 s 3) 79.0 s
2) 59.3 s 4) 118 s
14. Based on Reference Table N, what is the
fraction of a sample of potassium-42 that will
remain unchanged after 62.0 hours?
15. What is the half-life and decay mode of Rn-222?
1) 1.91 days and alpha decay
2) 1.91 days and beta decay
3) 3.82 days and alpha decay
4) 3.82 days and beta decay
16. Based on Reference Table N, what fraction of a
radioactive 90Sr sample would remain
unchanged after 56.2 years?
1) 1212
2) 1414
3) 1818
4) 116116
17. How many days are required for 200. grams of
radon-222 to decay to 50.0 grams?
1) 1.91 days 3) 7.64 days
2) 3.82 days 4) 11.5 days
18. Which radioisotope undergoes beta decay and
has a half-life of less than 1 minute?
1) Fr-220 3) N-16
2) K-42 4) P-32
19. Based on Reference Table N, what fraction of a
sample of gold-198 remains radioactive after
2.69 days?
1) 1414
2) 1212
3) 3434
4) 7878
20. After 32 days, 5 milligrams of an 80-milligram
sample of a radioactive isotope remains
unchanged. What is the half-life of this element?
1) 8 days 3) 16 days
2) 2 days 4) 4 days
21. According to Reference Table N, which
radioactive isotope will retain only one-eighth (1818
) its original radioactive atoms after
approximately 43 days?
1) gold-198 3) phosphorus-32
2) iodine-131 4) radon-222
22. According to Table N, which radioactive isotope
is best for determining the actual age of Earth?
1) 238U
2) 90Sr
3) 60Co
4) 14C
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Base your answers to questions 23 through 26 on on
the graph below. The graph represents the decay of
radioactive material X into a stable decay product.
23. If radioactive material X were heated, the length
of its half-life period would
1) decrease 3) remain the same
2) increase
24. Each of the objects below has different amounts
remaining of the original radioactive material X.
Which object is most likely the oldest?
1)
2)
3)
4)
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25. Which graph best represents the relative
percentages of radioactive material X and its
stable decay product after 15,000 years?(The
shaded region represents radioactive material
while the non-shaded region represents stable
decay products.)
1)
3)
2)
4)
26. What is the approximate half-life of radioactive
material X?
1) 5,000 yr 3) 50,000 yr
2) 10,000 yr 4) 100,000 yr
27. Exactly how much time must elapse before 16
grams of potassium-42 decays, leaving 2 grams
of the original isotope?
1) 8 12.4 hours 3) 3 12.4 hours
2) 2 12.4 hours 4) 4 12.4 hours
28. As a sample of the radioactive isotope 131I
decays, its half-life
1) decreases 3) remains the same
2) increases
29. The half-life of a radioactive substance is 2.5
minutes. What fraction of the original
radioactive substance remains after 10 minutes?
1) 1
2
2) 1
4
3) 1
8
4) 1
16
30. Approximately what fraction of an original
Co60 sample remains after 21 years?
1) 1
2
2) 1
4
3) 1
8
4) 1
16
31. The half-life of 131I is 8.07 days. What fraction
of a sample of 131I remains after 24.21 days?
1) 1
2
2) 1
4
3) 1
8
4) 1
16
32. What was the original mass of a radioactive
sample that decayed to 25 grams in four half-life
periods?
1) 50 g 3) 200 g
2) 100 g 4) 400 g
33. What is the total number of grams of a 32-gram
sample of 32P remaining after 71.5 days of
decay?
1) 1.0 g 3) 8.0 g
2) 2.0 g 4) 4.0 g
34. In how many days will a 12-gram sample of 13153 I
decay, leaving a total of 1.5 grams of the
original isotope?
1) 8.0 3) 20.
2) 16 4) 24
35. What mass of a 60.0-gram sample of 16N will
remain unchanged after 28.8 seconds?
1) 3.75 g 3) 15.0 g
2) 7.50 g 4) 30.0 g
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36. The half-life of 146 C is 5,730 years. What fraction
of a 1 gram sample of 146 C would remain after
17,190 years?
1) 1
2
2) 1
4
3) 1
8
4) 1
16
37. What is the number of half-life periods required
for a sample of a radioactive material to decay to
one-sixteenth its original mass?
1) 8 3) 3
2) 16 4) 4
38. A sample of 131I decays to 1.0 gram in 40. days.
What was the mass of the original sample?
1) 8.0 g 3) 32 g
2) 16 g 4) 4.0 g
39. Compared to 37K, the isotope 42K has a
1) shorter half-life and the same decay mode
2) shorter half-life and a different decay mode
3) longer half-life and the same decay mode
4) longer half-life and a different decay mode
40. What total mass of a 16 gram sample of 60Co
will remain unchanged after 15.9 years?
1) 1.0 g 3) 8.0 g
2) 2.0 g 4) 4.0 g
41. A 40.0 milligram sample of 33P decays to 10.0
milligrams in 50.0 days. What is the half-life of 33P?
1) 12.5 days 3) 37.5 days
2) 25.0 days 4) 75.0 days
42. If 8.0 grams of a sample of 60Co existed in 1990,
in which year will the remaining amount of 60Co
in the sample be 0.50 gram?
1) 1995 3) 2006
2) 2000 4) 2011
43. If 3.0 grams of 90Sr in a rock sample remained in
1989, approximately how many grams of 90Sr
were present in the original rock sample in 1933?
1) 9.0 g 3) 3.0 g
2) 6.0 g 4) 12. g
44. As a sample of a radioactive element decays, its
half-life
1) decreases 3) remains the same
2) increases
45. If 80 milligrams of a radioactive element decays
to 10 milligrams in 30 minutes, what is the
element's half-life in minutes?
1) 10 3) 30
2) 20 4) 40
46. An 80 milligram sample of a radioactive isotope
decays to 5 milligrams in 32 days. What is the
half-life of this element?
1) 8 days 3) 16 days
2) 2 days 4) 4 days
47. If a radioactive substance has a half-life of 9
days what fraction of its original mass would
remain after 27 days?
1) 1
8
2) 1
4
3) 1
2
4) 3
4
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48. The graph below represents the decay of a
radioactive isotope.
Based on Reference Table H, which
radioisotope is best represented by the graph?
1) 32P
2) 131I
3) 198Au
4) 222Rn
49. Which sample will decay least over a period of
30 days?
1) 10 g of Au-198 3) 10 g of P-32
2) 10 g of I-131 4) 10 g of Rn-222
50. As the temperature of a sample of a radioactive
element decreases, the half-life of the element
1) decreases 3) remains the same
2) increases
51. Which radioactive sample would contain the
greatest remaining mass of the radioactive
isotope after 10 years?
1) 2.0 grams of 198Au
2) 2.0 grams of 42K
3) 4.0 grams of 32P
4) 4.0 grams of 60Co
52. The graph below represents the decay curve of a
radioactive isotope. The half-life of this isotope
is
1) 8 years 3) 45 years
2) 30 years 4) 60 years
53. After 30 days, 5.0 grams of a radioactive isotope
remains from an original 40.-gram sample. What
is the half-life of this element?
1) 5 days 3) 15 days
2) 10 days 4) 20 days
54. Approximately how many grams of a 40-gram
sample of 13153 I will remain unchanged after 24
days?
1) 5 3) 13
2) 10 4) 20
55. The half-life of a radioactive isotope is 20.0
minutes. What is the total amount of a 1.00-
gram sample of this isotope remaining after 1.00
hour?
1) 0.500 g 3) 0.250 g
2) 0.333 g 4) 0.125 g
56. Which of the following radioisotopes has the
shortest half-life?
1) 14C
2) 3H
3) 37K
4) 32P
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57. A radioactive element has a half-life of 2 days.
Which fraction represents the amount of an
original sample of this element remaining after 6
days?
1) 1
8
2) 1
2
3) 1
3
4) 1
4
58. Which of the following 10-gram samples of
radioisotope will decay to the greatest extent in
28 days?
1) 3215P
2) 8536Kr
3) 22087 Fr
4) 13153 I
59. An original sample of a radioisotope had a mass
of 10 grams. After 2 days, 5 grams of the
radioisotope remains unchanged. What is the
half-life of this radioisotope?
1) 1 day 3) 5 days
2) 2 days 4) 4 days
60. The decay of which radioisotope can be used to
estimate the age of the fossilized remains of an
insect?
1) Rn-222 3) Co-60
2) I-131 4) C-14
61. Which isotope is most commonly used in the
radioactive dating of the remains of organic
materials?
1) 14C
2) 16N
3) 32P
4) 37K
62. Which isotopic ratio needs to be determined
when the age of ancient wooden objects is
investigated?
1) uranium-235 to uranium-238
2) hydrogen-2 to hydrogen-3
3) nitrogen-16 to nitrogen-14
4) carbon-14 to carbon-12
63. Which procedure is based on the half-life of a
radioisotope?
1) accelerating to increase kinetic energy
2) radiating to kill cancer cells
3) counting to determine a level of radioactivity
4) dating to determine age
64. A radioactive-dating procedure to determine the
age of a mineral compares the mineral's
remaining amounts of isotope 238U and isotope
1) 206Pb
2) 206Bi
3) 214Pb
4) 214Bi
65. The course of a chemical reaction can be traced
by using a
1) polar molecule 3) stable isotope
2) diatomic molecule 4) radioisotope
66. The radioisotope I-131 is used to
1) control nuclear reactors
2) determine the age of fossils
3) diagnose thyroid disorders
4) trigger fussion reactors
67. Radioisotopes used for medical diagnosis must
have
1) long half-lives and be quickly eliminated by
the body
2) long half-lives and be slowly eliminated by
the body
3) short half-lives and be quickly eliminated by
the body
4) short half-lives and be slowly eliminated by
the body
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68. A radioisotope which is sometimes used by
doctors to pinpoint a brain tumor is
1) carbon-12 3) technetium-99
2) lead-206 4) uranium-238
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Reference Tables
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Reference Tables
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Reference Tables
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Reference Tables
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Answer KeyAnswer Key
1. 1
2. 4
3. 2
4. 2
5. 2
6. 2
7. 1
8. 4
9. 1
10. 4
11. 2
12. 4
13. 2
14. 132132 or 0.3125
15. 3
16. 2
17. 3
18. 3
19. 2
20. 1
21. 3
22. 1
23. 3
24. 1
25. 3
26. 1
27. 3
28. 3
29. 4
30. 4
31. 3
32. 4
33. 1
34. 4
35. 1
36. 3
37. 4
38. 3
39. 4
40. 2
41. 2
42. 4
43. 4
44. 3
45. 1
46. 1
47. 1
48. 2
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Answer Key
49. 3
50. 3
51. 4
52. 2
53. 2
54. 1
55. 4
56. 3
57. 1
58. 3
59. 2
60. 4
61. 1
62. 4
63. 4
64. 1
65. 4
66. 3
67. 3
68. 3