The half-life of Radium-223 is 11.43 days. If a sample has a mass
of 900 mg, find the mass (in mg) that remains after
5 days
78.7mg
393.7mg
To find the mass that remains after 5 days, we can use the formula for exponential decay:
A = A₀ * (1/2)^(t / half-life)
Where:
A = final amount or remaining mass
A₀ = initial amount or starting mass
t = time elapsed
half-life = time it takes for half of the sample to decay
In this case, the initial amount or starting mass (A₀) is 900 mg, the time elapsed (t) is 5 days, and the half-life is 11.43 days.
Let's substitute these values into the formula:
A = 900 mg * (1/2)^(5 / 11.43)
Calculating the exponential:
A ≈ 900 mg * 0.8622
A ≈ 775.98 mg
Therefore, after 5 days, approximately 775.98 mg of the sample remains.