AOK decays to 40Ar with a half-life of 1.25 x 10° yr. Assume that rocks contain no 40Ar when they form, and that the only way 4Ar can be present is through the decay of 40K. If the ratio of 40K to 40Ar in a particular rock is found to be 1:3, what is the age of the rock?

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i can confirm answer 5118 years is wrong

Modern household smoke detectors contain a tiny speck of the element Americium (Am, atomic number 95, atomic mass 241), which has a half-life of 432 years and an activity of (roughly) of 37,000 decays per second. a) What is the approximate mass of this speck? (Hint: the atomic mass of this isotope is approximately 241.06 u). b) This isotope is an alpha emitter. Is its radiation likely to be a hazard to the household members while the smoke detector is on the ceiling? Explain.

A state-of-the-art proton decay experiment is expected to detect 47% of the proton decays in a body of water. Assuming protons have a lifetime of 1031 years, how many m3 of water would you need in order to see 6 decays per month?  (Assume a "month" is one-twelfth of a year.)

Calculate the binding energy per nucleon of the carbon nucleus, 612?. (Given mass of proton = 1.007276 u, mass of neutron = 1.008665 u, mass of electron = 0.000549 u and mass of Carbon-12 atom = 12.000000 u)

The theory of nuclear astrophysics is that all the heavy elements like uranium are formed in the interior of massive stars. These stars eventually explode, releasing the elements into space. If we assume that at the time of explosion there were equal amounts of 235U and 238U, 235 how long ago were the elements that formed our Earth released, given that the present U/238U ratio is 0.007? (The half-lives of 235u and 238U are 0.70 × 10° yr and 4.47 x 10° yr, respectively.) years

The isotope ¹C has a half-life of 5730 years. What percent (N/No) of the ¹4C in a buried animal 14 bone will remain after 45,000 years?

14C has an activity of 0.25 Bq per gram of carbon for living organisms. The half-life of 14C is 5730 years. If a sample of charcoal from an archeological dig yields a 14C activity of 0.15 Bq per gram of carbon, how old is the material?