A hospital receives 16 g of iodine-131 (molar mass ≈131 g mol−1) to be used in thyroid treatment. The half-life of iodine-131 is 8.0 days.
(a) Calculate the mass of iodine-131 that will remain undecayed after 24 days.
(b) Initially, the activity of the sample is 3.40×1014 decays s−1. Determine the activity that will be available after 24 days, assuming none of the iodine is lost by any process other than radioactive decay.
(Take Avogadro constant NA=6.02×1023mol−1.)