Consider a pure sample of a radioactive isotope with a mass number of (50).  If the sample has mass of (25.0) micrograms and the isotope has a half-life of (17.5)x106 years, determine the decay rate for the sample.   Give your answer in decays/second and with 3 significant figures.

A nuclear physicist finds 1.0of 236Uin a piece of uranium ore (T1/2=2.348107y) . (a) Use die decay law to determine how much 236Uwould had to have been on Earth when it formed 4.543109yago for 1.0gto be left today, (b) What is unreasonable about this result? (c) How is this unreasonable result resolved?

Calculate the dose in Sv to the chest at a patient given an xray under the following conditions. The xray beam intensity is 1.50 W/m2, the area of the chest exposed is 0.0750 m2 35.0% of the xrays are absorbed in 20.0 kg of tissue, and the exposure time is 0.250 s.

The atomic weight of cadmium is 112.41, and its density is 8.65 g/cm3. Using Figure 14.3, estimate the attenuation distance of a thermal neutron beam in cadmium. (The attenuation distance is the distance traveled after which the intensity of the beam is reduced to 1/e of its initial value, where e is the base of the natural logarithms.)

Which of the following is the correct daughter nucleus associated with the beta decay of 72184Hf? (a) 72183Hf (b) 73183Ta (c) 73184Ta

(a) Calculate the energy released in the a decay of 238U . (b) What fraction of the mass of a single 238U is destroyed in the decay? The mass of 234Th is 234.043593 u. (c) Although the fractional mass loss is large for a single nucleus, it is difficult to observe for an entire macroscopic sample of uranium. Why is this?

Data from the appendices and the periodic table may be needed for these problems. 44. An old camp?re is uncovered during an archaeological dig. Its charcoal is found to contain less than 1/1000 the normal amount of 14C. Estimate the minimum age at the charcoal, noting that 210 = 1024.