Multiple ChoiceHow long will it take for 80% of a 1.20-mg sample of Rn-220 to decay? The half-life of Rn-220 is 55.6 s.267views
Multiple ChoiceA sample of Th-219 requires 3.84 × 10−6 seconds to decay to 1.50 mg. What was the initial mass of the sample of Th-219? (t 1/2 for Th-219 = 1.05 × 10−6 s)261views
Multiple ChoiceHow many mg of a 3.50-mg sample of Tc-99 will remain after 4 half-lives have passed?240views
Multiple ChoiceFor the radioactive decay of lead-202 the decay constant is 1.32 x 10-5 yr-1. How long will it take in hours to decrease to 53% of its initial amount?218views
Multiple ChoiceDuring World War I radium-226 was used in the manufacturing of luminous paint. If it takes 2.12 x 104 days for its degradation to be 2.49% complete, what is its decay constant?205views
Multiple ChoiceIf the decay constant for polonium-209 is 6.80 x 10-3 ys-1, what fraction of it remains after 1.1 x 104 years?205views
Open QuestionA fossil is found to have a 14c level of 64.0% compared to living organisms. How old is the fossil?172views
Open QuestionA fossil is found to have a 14C level of 85.0% compared to living organisms. How old is the fossil?168views
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