Isotopes and Radioactive Decay. Calculate the total radioactivity that results from one isotope in the human body. Must understand the concepts of half-life, decay constant, DPM, decay.

K40 (half-life=1.3x10E9 years) composes approximately 0.012% of the potassium found in nature. By weight, the human body is approximately 0.35% potassium. Calculate the total radioactivity that results from K40 decay in a 75 kg human.

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...e: Calculate the total amount of K40 found in the 75 kg human.

Total K40 = 0.012% (K40 in nature) * 0.35% (total K in human) * 75 kg
Total K40 = 3.15x10-2 g

Step two: Convert the mass of K40 found in the 75 kg human to the number of atoms of K40 in the human. (You will need the molecular mass of K40 (40 g per mole), as well as Avogadro's number (6.023x1023 atoms per mole)).

# of K40 atoms = 3.15x10-2g * (1 mole/40 g)*(6.023x1023 ...