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9 Cards in this Set
- Front
- Back
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Which of the following radioactive dating method is used to date relatively recent events? uranium isotopes rubidium isotopes radiocarbon dating relative dating potassium-argon isotopes |
radiocarbon dating |
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The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half-lives have elapsed since the material was 100% parent atoms? between l and 2 between 2 and 3 less than l more than 3 |
between l and 2 |
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The half-life of carbon-14 is about 6000 years. Assume that a sample of charcoal formed by burning of living wood 15,000 years ago. How much of the original carbon-14 would remain today? more than 50% between 25% and 50% between 12.5% and 25% between 33% and 50% |
between 12.5% and 25% |
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The percentage of radioactive atoms that decay during one half-life is always the same. True False |
True |
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After two half-lives there is no longer any of the original radioactive material remaining. True False |
False |
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After three half-lives, one-ninth of an original, radioactive parent isotope remains and eight-ninths has decayed into the daughter isotope. True False |
False |
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Numerical age dates based on radioactivity are very important for studying Precambrian geologic history because fossils are rare or absent. True False |
True |
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Consider the names of the eras in the geologic time scale. What is meant by "zoic"? rocks; lithified strata time; recording of events places; geographic references life; living things |
life; living things |
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Most sedimentary rocks are readily dated by radiometric methods. True False |
false |
