
A 64g sample of Germanium-66 is left undisturbed for 12.5 hours. At the end of that...
70. The half-life of cobalt-60 is 5.3 years. What percent of a sample of cobal:-60 will remain after 21.2 years? A) 50% B) 40% C) 12.5% D) 10% E) 6.25%
91. If the half – life of a sample of radioactive material is 60 days, what fraction of the original radioactive nuclei will remain after 120 days.
An isotope of cesium (Cesium-137) has a half-life of 30 years. If 1.0 mg of cesium-137 disintegrates over a period of 90 years, how many mg of cesium-137 would remain? 14. Thallium-208 has a half-life of 3.053 min. How long will it take for 120.0g to decay to 7.500 15. Element-106 has a half-life of 0.90 seconds. If one million atoms of it were prepared, how many atoms would remain after 4.5 seconds? 16. A 2.5 gram sample of an...
A radioactive sample has a half-life of 10 minutes. What fraction of the sample is left after 40 minutes ? 1/2 1/4 1/8 1/16 Which one is correct ?
The radioactive isotope thorium 234 has a half-life of approximately 578 hours. (a) If a sample has a mass of 67 milligrams, find an expression for the mass after t hours. Q(t) = 67e-0.0011997 (b) How much will remain after 85 hours? (Round your answer to one decimal place.) 60.5 mg (c) When will the initial mass decay to 20 milligrams? (Round your answer to one decimal place.) 1008.3 x hr
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Copper -64 is radioactive and has a half life of 12.7 hours. The sample that initially contains 3mh of Cu-64, How much time will it take for only .5mg to remain. Find the pH of a solution .15M of propionic acid. Ka for the acid is 1.3 times 10^-5
1. For a first order decay of [A], if 525 mg remains of an initial sample of 1.3079 g after 361 min, what is the half life (in minutes)? 2. The decay of antimony-131 is first order with a half life is 23.03 minutes. How much of 1.4228 g sample would remain after 1.368 hours? 3. The decay of antimony-131 is first order with a half life is 23.03 minutes. How long (in minutes) would it take for a 0.8893...
Submit 1128.0% of a sample of silver-112 decays in 1.52 hours, what is the half-life of this isotope (in hours)? hours 12 3 6 4 0 x10口
A sample of a certain radioactive substance is prepared, and its initial activity is 4 µCi. After 2.4 hours, the activity is measured to be 1 µCi. What is the half-life of this material?
8. A. Calculate the amount of radioactive material left of a 255g sample, after 30 days, whose life is 6 days (12 pts) B. Write out the products of a particle decay of the Thorium nucleus below. 234 Th 90 C. True or False. In a nuclear reaction changes occur in the nucleus of the atom only.