Question :
61. Carbon-14 has a half-life of 5730 yr. A living : 1335562
61. Carbon-14 has a half-life of 5730 yr. A living organism has an activity of 15.2 counts per minute (cpm) per gram of carbon. If a bone is determined to have an activity of 3.80 cpm per gram of carbon, how old is the bone?
A) 5730 yr B) 17,200 yr C) 22,900 yr D) 8600 yr E) 11,500 yr
62. Carbon-14 has a half-life of 5730 yr. A living organism has an activity of 15.2 counts per minute (cpm) per gram of carbon. If a bone is determined to have an activity of 1.90 cpm per gram of carbon, how old is the bone?
A) 5730 yr B) 17,200 yr C) 22,900 yr D) 8600 yr E) 11,500 yr
63. Carbon-11 radioactively decays by positron emission with a half-life of 20.4 minutes. If a dosage of carbon-11 is administered to a patient for a PET scan, what percentage of carbon-11 will remain in the patient’s system after 61.2 min?
A) 75.0% B) 12.5% C) 87.5% D) 25.0% E) 50.0%
64. Carbon-11 radioactively decays by positron emission with a half-life of 20.4 minutes. If a dosage of carbon-11 is administered to a patient for a PET scan, what percentage of carbon-11 will remain in the patient’s system after 81.6 min?
A) 75.0% B) 12.5% C) 87.5% D) 25.0% E) 6.25%
65. Which of the following statements regarding the possible effects of radiation on a cell is incorrect?
A)Radiation can pass through a cell with no damage.
B)Radiation can damage a cell, but it is possible for the cell to repair the damage.
C)Radiation may damage a cell so severely that it cannot repair itself.
D)A damaged cell may mutate, and cause cancer.
E)The degree of damage does not depend on the ionizing ability of the radiation.
66. Which of the following statements regarding nuclear stability is incorrect?
A)The N/Z ratio is about 1 for the first 20 elements.
B)The N/Z ratio is about 1.6 for elements at the upper end of the band of stability.
C)An N/Z ratio of 1 means that an element has an equal number of protons and electrons.
D)Elements outside the band of stability are radioactive.
E)All isotopes with Z greater than 83 are radioactive.
67. Which of the following statements regarding nuclear stability is incorrect?
A)Isotopes with excess mass tend to undergo alpha decay.
B)Isotopes with an N/Z ratio that is too high tend to undergo beta decay.
C)Isotopes with an N/Z ratio that is too low tend to undergo either positron emission or electron capture.
D)Electron capture is the most common mode of decay for smaller isotopes.
E)An energetically excited nucleus can undergo gamma emission.
68. What product is formed when undergoes 5 alpha emissions and 2 beta emissions in a total of seven steps?
A)mercury-214D)mercury-204
B)polonium-214E)plutonium-239
C)polonium-224
69. What product is formed when undergoes 2 alpha emissions and 2 beta emissions in a total of four steps?
A) lead-234 B) radon-234 C) thorium-230 D) radon-232 E) radon-228
70. What product is formed when undergoes 6 alpha emissions and 3 beta emissions in a total of nine steps?
A)lead-223D)bismuth-214
B)mercury-223E)lead-214
C)mercury-226
