Radioactive 131I has a half-life of 8.0 days. A sample containing 131I has activity 20 μ Ci at t = 0.
(a) What is its activity at t = 4.0 days?
(b) What is its decay constant at t = 4.0 days?
Given,
Half-life = 8 days, A0 = 20μCi
a) We know that,
Where,
A= Activity of the substance
A0 = Initial activity
t = time
λ = decay constant
So,
b) Decay constant in per second s-1