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A radioactive isotope has an activity of 9.94×104 Bq initially. After 3.35 hours the activity is 5.96×104 Bq. What is the half-life of the isotope?       What is the activity after an additional 3.35 hours?

A sample of charcoal from a ceremonial fire pit was determined to have a radiation count of 4.28 counts/sec from 14C radioactivity. If a living piece of wood displays 7.83 counts/second for the same type and size sample, how old is the piece of charcoal (assuming the wood was burned shortly after it died)? The half-life of 14C is 5730 years. O 4200 years 5000 years O 7200 years O 6700 years

A radioactive sample contains 9.5 x 1017 atoms of a nuclide that decays at a rate of 5.4 x 1013 disintegrations per 20 min. What percentage of the nuclide will have decayed after 200 days? How many atoms of nuclide will remain in the sample? What is the half-life of the nuclide?

The half-life of cesium-129 is 32.0 hours. How much time is required for the activity of a sample of cesium-129 to fall to 13.7 percent of its original value? hrs

Am-241 is a radioactive isotope that decays by alpha emission. Each alpha particle emitted carries 8.79E-13 J of kinetic energy.A 80.0 kg worker is accidentally exposed to a sample of Am-241 having an activity of 0.0250 curies for a total of 10.00 minutes. During that time the workers body absorbs 2.50 percent of the alpha particles emitted by the sample.How many alpha particles were emitted by the sample during the time of the workers exposure? Answer: alpha particles emittedHow many joules of energy were absorbed by the worker? Answer: JoulesThe alpha particles emitted by the sample have an RBE=20. Calculate the workers exposure in millirems. Exposure = _____ millirems

A wood carving is found in the excavation of an abandoned settlement. A sample from this carving is found to have a C-14 content that is 25.0% of that of living trees. How old is the object? The half-life of carbon 14 is 5730 years.

Iodine-125 is a radioactive isotope commonly used in medicine. It has a half-life of 59.5 days. Suppose at the start of Day 1 you store 3.77 kg of Iodine-125 in a cabinet and do not use it. After 119 days, how much Iodine-125 will you have (in kg)?