Radioactivity
posted by Anonymous .
How are the terms "activity" and "becquerel" related?
A radioactive isotope source has a mass of 120 g. If the isotope has a half life of 20 secs what would be the mass of the isotope in 2 mins?

k = 0.693/t_{1/2}
Substitute k into the equation below.
ln(No/N) = kt
No = 120
N = ?
k from above
t = 120 seconds (since the half life is given in sec you will have a seconds terms for k so you must convert 2 minutes to seconds).
Solve for N.
See the link below for the definition of Bq.
http://en.wikipedia.org/wiki/Becquerel
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