Chapter 42: Q 19 Exercise (page 1236)
The radium isotope 226Ra has a half-life of 1600 years. A
sample begins with 1.00x1010 226Ra atoms. How many are left
after (a) 200 years, (b) 2000 years, and (c) 20,000 years?
Short Answer
Therefore,
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Chapter 42: Q 19 Exercise (page 1236)
The radium isotope 226Ra has a half-life of 1600 years. A
sample begins with 1.00x1010 226Ra atoms. How many are left
after (a) 200 years, (b) 2000 years, and (c) 20,000 years?
Therefore,
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What is the half-life in days of a radioactive sample with 5.0 x 1015
atoms and an activity of 5.0 x 108 Bq?
Could a nucleus fission into two nuclei? Your answer, which should include some calculations, should be based on the curve of binding energy.
Calculate (in ) the binding energy per nucleon for and . Which is more tightly bound?
Apple A in FIGURE Q42.8 is strongly irradiated by nuclear radiation for 1 hour. Apple B is not irradiated. Afterward, in what ways
are apples A and B different?
The plutonium isotope 239 Pu has a half-life of 24,000 years and decays by the emission of a 5.2 MeV alpha particle. Plutonium is not especially dangerous if handled because the activity is low and the alpha radiation doesn’t penetrate the skin. However, there are serious health concerns if even the tiniest particles of plutonium are inhaled and lodge deep in the lungs. This could happen following any kind of fire or explosion that disperses plutonium as dust. Let’s determine the level of danger. a. Soot particles are roughly 1 mm in diameter, and it is known that these particles can go deep into the lungs. How many atoms are in a 1.0@mm@diameter particle of 239 Pu? The density of plutonium is 19,800 kg/m3 . b. What is the activity, in Bq, of a 1.0@mm@diameter particle? c. The activity of the particle is very small, but the penetrating power of alpha particles is also very small. The alpha particles are all stopped, and each deposits its energy in a 50@mm@diameter sphere around the particle. What is the dose, in mSv/year, to this small sphere of tissue in the lungs? Assume that the tissue density is that of water. d. Is this exposure likely to be significant? How does it compare to the natural background of radiation exposure?
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