The decay constant of the radioactive iodine is r =0.086625
Now,
Let N be the size of a population of radioactive atoms at a given time t, and dN, the amount by which the population decreases in time dt
So that the rate of change is given by
dN/dt = −λN, ((where λ is the decay constant).
By Integration, We have
N = N0e−λt, ( where N0 is the size of an initial population of radioactive atoms at time t = 0)
We can see that the population decays exponentially which is dependent on the decay constant.
Therefore, for a radioactive iodine with half life of 8days , The decay constant will be
λ = 0.693/ T1/2 or
r = 0.693/ T1/2
r = 0.693/ 8days
r =0.086625
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