Question

Cesium-137 has a decay constant of 0.0231 (a 30-year half-life). If you start with 15 pounds of cesium-137, how much will still be there 30 years later? Round to the nearest tenth.

Answer 1

N = 7.5 pounds

Explanation:

Formula for the radioactive decay is given by,

`N=N_0e^(-\lambda t)`

Here, N = Final amount

N₀ = Initial amount

λ = Decay constant

t = Duration of decay

Now we can substitute the values from the given question,

N =
`15e^(-(0.0231* 30))`

N =
`15e^(-0.693)`

N = 15(0.5)

N = 7.5 pounds