(adsbygoogle = window.adsbygoogle || []).push({}); Help!!! calculating the the activity of a radioactive sample!!

1. find activity R

2. the average 70 KF males contain 140 gram of potassium. of this 0.012% is potassium 40. the half life of potassium 40 is 1.2 billion years. so how many K40 decay per second and what is the activity of K40 in the body??

3. so my solution here is..

140g = 0.14kg

and mass of K40 = 0.14 * 0.012/100 = 1.68 * 10^-5kg

how many decay per second = (1.68*10^-5)/2 / 3600*24*365*1.2*10^12 = 2.22*10^-25kg

then i use R = [tex]\lambda[/tex] * N = 0.653N/half life

= 3.88 * 10^-45 Bq

but this answer is wrong!!! cuz the correct one is 4200 Bq

so help me plz!!! thx

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# Homework Help: Help calculating the the activity of a radioactive sample

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