Question

The half-life of cobalt-60 is 5.26 years. If 0.000643 g are left after 100. years, how manygrams were in the original sample?

Answer 1

Given data

*The half-life of cobalt-60 is t = 5.26 years

*The quantity left is N = 0.000643 g

*The given time is T = 100 years

From the radioactivity decay equation, it is given as

$N=n(0.5)^{\frac{T}{t}}$

Substitute the values in the above expression as

$\begin{gathered} 0.000643=n(0.5)^{\frac{100}{5.26}} \\ n=3397.9\text{ g} \end{gathered}$