Biologically useful technetium nuclei(with atomic weight 99) have half life of 6 hours.a solution conatning `10^(-12)` gram of this is injected into the bladder of a patient .Find its activity at the beginning and after one hour.

The normal activity of living carbon-containing matter is found to be about 15 decays per minute for every gram of carbon. This activity arises from the small proportion of radioactive "_6^14C present with the stable carbon isotope "_6^12C . When the organism is dead, its interaction with the atmosphere (which maintains the above equilibrium activity) ceases and its activity begins to drop. From the known half-life (5730 years) of "_6^14C , and the measured activity, the age of the specimen can be approximately estimated. This is the principle of "_6^14C dating used in archaeology. Suppose a specimen from Mohenjodaro gives an activity of 9 decays per minute per gram of carbon. Estimate the approximate age of the Indus-Valley civilisation.

The half-life of Tc^(99) is 6.0 hr. The total residual activity in a patient 30 hr after receiving an injection containing Tc^(99) must be more than 0.01 muC_(i) . What is the maximum activity ("in"muC_(i)) that the sample injected can have? a) 0.16 b) 0.32 c) 0.64 d) 0.08

In an experiment,the activity of 1.2 milligram(mg) of radioactive potassium chloride (chlroide of isotopeK_40) was found to be 170s^(-1) .Taking molar mass of K-40Cl to be 0.075 kg mole ^(-1),find the number of K-40 atoms in the sample and hence find the half-life of K-40 .Given ,Avogadro number =6.0 x 10^(23) mole^(-1).