21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Question
Chapter 8, Problem 41QP
(a)
To determine
The number of half-lives will the sample have remaining only
(b)
To determine
The time taken to complete six half-lives.
(c)
To determine
Whether it is possible to overestimate or underestimate the age of a sample if daughter nuclei were present in the sample when it formed.
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Students have asked these similar questions
A sample of carbon-14 initially consists of 5 × 10 24 particles. Carbon-14 has a half- life of 5730 years.
a. What is the decay constant for carbon-14? (Answer in units of yr –1 .)
b. How many radioactive particles of the sample remain after 100 years?
c. What percentage of the radioactive particles remains after 500 years?
d. How many radioactive particles of the sample remain after 1000 years?
e. How much time will it take for 50% of the particles to decay?
f. How much time will it take for 99% of the particles to decay?
g. How many half-lives will it take for 99% of the sample to decay?
h. What is the initial decay rate of the sample? (Answer in decays/yr.)
i. After 200 years, what is the decay rate of the sample?
j. How long will it take for the decay rate to decrease to 1015 decays/year?
k. How many half-lives have passed after the time you found in part (j)?
What is "half-life"?
Select one:
a. The time needed for half of the radioactive atoms in a sample to decay
b. the time needed for a radioactive atom to lose half its energy
c. the time needed for the mass of a radioactive atom to decrease by one-half
5. If a 10-gram sample of a radioactive substance has a half-life of 6000 years, how much would be present after 8000 years?
6. If Nitrogen-14 absorbs an alpha particle and then emits a Hydrogen-1, what is the resulting nucleus?
Chapter 8 Solutions
21st Century Astronomy
Ch. 8.1 - Prob. 8.1CYUCh. 8.2 - Prob. 8.2CYUCh. 8.3 - Prob. 8.3ACYUCh. 8.3 - Prob. 8.3BCYUCh. 8.4 - Prob. 8.4CYUCh. 8.5 - Prob. 8.5CYUCh. 8.6 - Prob. 8.6CYUCh. 8 - Prob. 1QPCh. 8 - Prob. 2QPCh. 8 - Prob. 3QP
Ch. 8 - Prob. 4QPCh. 8 - Prob. 5QPCh. 8 - Prob. 6QPCh. 8 - Prob. 7QPCh. 8 - Prob. 8QPCh. 8 - Prob. 9QPCh. 8 - Prob. 10QPCh. 8 - Prob. 11QPCh. 8 - Prob. 12QPCh. 8 - Prob. 13QPCh. 8 - Prob. 14QPCh. 8 - Prob. 15QPCh. 8 - Prob. 16QPCh. 8 - Prob. 17QPCh. 8 - Prob. 18QPCh. 8 - Prob. 19QPCh. 8 - Prob. 20QPCh. 8 - Prob. 21QPCh. 8 - Prob. 22QPCh. 8 - Prob. 23QPCh. 8 - Prob. 24QPCh. 8 - Prob. 25QPCh. 8 - Prob. 26QPCh. 8 - Prob. 27QPCh. 8 - Prob. 28QPCh. 8 - Prob. 29QPCh. 8 - Prob. 30QPCh. 8 - Prob. 31QPCh. 8 - Prob. 32QPCh. 8 - Prob. 33QPCh. 8 - Prob. 34QPCh. 8 - Prob. 35QPCh. 8 - Prob. 36QPCh. 8 - Prob. 37QPCh. 8 - Prob. 38QPCh. 8 - Prob. 39QPCh. 8 - Prob. 40QPCh. 8 - Prob. 41QPCh. 8 - Prob. 42QPCh. 8 - Prob. 43QPCh. 8 - Prob. 44QPCh. 8 - Prob. 45QP
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Similar questions
- If a 1.50-cm-thick piece of lead can absorb 90.0% of the rays from a radioactive source, how many centimeters of lead are needed to absorb all but 0.100% of the rays?arrow_forward5. Co-60 has a half life of 5.3 years. If a pellet that has been in storage for 26.5 years contains 14.5g of Co-60, how much of this radioisotope was present when the pellet was put in storage?arrow_forward866-0 hours. A radioactive sample contains 1.55g of of an isotope with half a life of 3.8 days. How much of the in grams remain after 150 tope 11.4 days?arrow_forward
- B5. A living tree has a carbon-14 decay rate of 13.6 counts per minute per gram. An old dried piece of wood from the same type of tree has a decay rate of 3.4 counts per minute per gram. (a) Estimate the age of the old piece of wood. The half life of carbon-14 is 5730 years. (b) How many counts per minute per gram will be measured if the wood was 18,000 years old? Express the values to 3 significant figures, if necessary.arrow_forwardWhy are some radioactive substances dangerous for a very long time? Select one: a. Some radioactive substances have very long half-lives. It takes a long time for the number of radioactive atoms to decrease. b. Some radioactive atoms combine easily with minerals in the ground, so they can't be removed from the environment. c. Some radioactive atoms combine easily with organic molecules. They get into the food chain where they can't be removed. d. Some radioactive molecules are very light, so they stay in the air for long periods of time.arrow_forwardDATE NAME Half-life Practice 1. What is half-life? 2. If we start with 400 atoms of a radioactive substance, how many would we have after: a. one half-life? b. two half-lives? c. three half-lives? d. four half-lives? 3. If we start with 48 atoms of a radioactive substance, how many would remain after: a. one half-life? b. two half-lives? c. after three half-lives? d. after four half-lives? Using the graph to the right, answer the following questions. 4. What is the half-life of each element? 5. Which element has the shortest half-life? 10- 6. Which element is the most unstable? How do you know? Ago 10 years ) Use the graph on the to answer the following questions. 7. How many atoms are in the original sample size of this radioisotope? 8. How long is the half-life? 9. How many atoms are left after 2 half-lives? 10. Approximately how many days would have to pass for there to be only 2.5 atoms of the sample remaining? How many half-lives? Parcent ot Oniginal Mase Romainingarrow_forward
- Fukushima Unit-2 produced approximately 3200 MW of thermal power. Assume it had operated for 16 months before the tsunami and then was shut down for 20 days before the any radioactive material was released. a. How much fission product activity was present in the core at the time of the accidental release? b. Assuming 2 MeV per radioactive decay (1 MeV from a beta and 1 Mev from a gamma), and that all of the energy was deposited into the reactor core and coolant, how much heat (in MW) was being produced by the fission product activity on the 20th day?arrow_forwardA sample from human remains found near Stonehenge in England shows that 71.2% of the carbon-14 still remains. Use the model Q(1) = Qe-0.000121 to determine the age of the sample. In this model, Q(t) represents the amount of carbon-14 remaining t years after death, and Qo represents the initial amount of carbon-14 at the time of death. Round to the nearest 100 yr.arrow_forwardQ2) Since the half-life of U-235 (7.13x108 years) is less than that of U-238 (4.51x 10⁹ years). The isotopic abundance of U-235 has been steadily decreasing since the earth was formed about 4.5 billion years ago. Determine how long ago the isotopic abundance of U-235 was equal to 3.0 weight percent, that is, the enrichment of the uranium used in many nuclear power plants. The present day isotopic abundance of U- 235 is 0.72%.arrow_forward
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