The half-life for beta decay of strontium-90 is 28.8 years.A milk sample is found to contain 10.3 ppm strontium-90.How many years would pass before the strontium-90 concentration would drop to 1.0 ppm?

Question

Quizplus · Accepted Answer

First, we need to determine the decay constant (λ) using the half-life:

t½ = 28.8 years
λ = ln(2)/t½ = 0.024/years

Next, we can use the radioactive decay equation to find the time it takes for the concentration to decrease from 10.3 ppm to 1.0 ppm:

N(t) = N0e^(-λt)

where N(t) is the concentration at time t, N0 is the initial concentration, and e is the mathematical constant approximately equal to 2.718.

We can rearrange this equation to solve for t:

t = (ln(N0/N))/λ

Plugging in the values we know:

N0 = 10.3 ppm
N = 1.0 ppm

t = (ln(10.3/1.0))/0.024 = 96.9 years

Therefore, the answer is D) 96.9.

The Half-Life for Beta Decay of Strontium-90 Is 28