Question

An isotope has a half life of 102 years. How much of a 22gram sample is left after 250 years?

Answer 1

The formula for finding the half life is

Final amount= initial amount * 0.5^(time/half life)

Final amount = 22*0.5^(250\102)
= 22^0.5^(2.4509..)
= 22*0.18288..
= 4.02350054
=4.02g

Hope this helps!

Answer 2

A half life of 102 years means a decay formula something like

`A = A_0 * 2^(-t/102)`

When t=250,

`(A)/(A_0) = 2^(-250/102) \approx 0.182886`

Answer: 18.3%