A 70 kg human body typically contains 140 g of potassium. Potassium has a chemic

Question

A 70 kg human body typically contains 140 g of potassium. Potassium has a chemical atomic mass of 39.1 u and has three naturally occurring isotopes. One of those isotopes, 40K, is radioactive with a half-life of 1.3 billion years and a natural abundance of 0.012 %. Each 40K decay deposits, on average, 1.0 MeV of energy into the body.

question:
What yearly dose in Gy does the typical person receive from the decay of 40K in the body? Express your answer using two significant figures.

Q=________Gy

Please show work. Thanks!

Explanation / Answer

        Absorbed energy    A = 1.0 *106 ( 1.6*10-19 J   / eV) = 1.6*10-3 J      mass of the human body m = 70 kg         Absorbed dose    = energy /mass =   (1.6*10-3 J ) /  70 kg     = 0.0228*10-3 J/kg          Aborbed dose   = 2.28*10-5 Gy

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