Answer:
1.115 g
Explanation:
Applying,
R = R'[tex]2^{n/t}[/tex]................... Equation 1
Where R = original sample of radon-222, R' = sample of radon-222 left after decay, n = Total time, t = half-life.
make R' the subject of the equation
R' = R/([tex]2^{n/t}[/tex])............... Equation 2
From the question,
Given: R = 73.9 g, n = 23 days, t = 3.8 days.
Substitute these values into equation 2
R' = 73.9/([tex]2^{23/3.8}[/tex])
R' = 73.9/[tex]2^{6.05}[/tex]
R' = 1.115 g