a.[3]
A clinical sample of Iodine-131, used in thyroid therapy, has a half-life of 8 days8\text{ days}8 days. Initially, the sample contains 240 mg of this isotope.
Determine the mass of Iodine-131 remaining in the sample after 32 days32\text{ days}32 days.
b.[1]
The graph below shows the radioactive activity emitted from samples of three different isotopes, A, B, and C, over a period of 15 days15\text{ days}15 days.
Which isotope, A, B, or C, has the longest half-life?
c.[3]
Explain why isotope A is initially more hazardous than isotope B, but becomes less hazardous than isotope B after 3 days3\text{ days}3 days.