During the testing process for some pharmaceuticals, the drug is \"tagged\" with a radioactive material. This way researchers can determine if the pharmaceutical is going to other parts of the body than the intended target and what effect it has on the non-target areas. By adding this radioactive tag to the pharmaceutical, researchers can pinpoint all parts of the body and the concentration that accumulates in non-target areas.
One possible such tag is technetium-99, 99Tc, which has a half-life of 6.05 hours.
1) How many 99Tc nuclei are required to give an activity of 1.6 oCi?
2) What is the decay constant for this isotope?
3) Suppose the drug containing the amount of 99Tc calculated in part (a), were injected into the patient 1.35 hours after it was prepared, what would its activity be at that time?