1. A 2 kg sample of a radioisotope is used in medical procedures. The radioisotope is observed to decrease in mass by 1.75 kg over a period of 12 minutes.

a. Determine the half-life of the sample. (2 marks)
b. If a 12 mg sample is required for a medical procedure and the isotope is produced in a laboratory 1 hour away, how much of the radioisotope needs to be produced? (3 marks)
c. The sample is placed on a set of scales and is observed over a period of time. Explain why the mass measured by the scales does not appear to decrease. (2 marks)

2. A 2.5 kg meteorite shows a Carbon-14 activity of 500 mBq. Archaeologists compare this to a freshly obtained bone, of mass 10 g which has an activity of 64 mBq. How much older is the meteorite than the bone? (4 marks)

So far I'm able to determine the half life of 1A.