Question

1. A 50 gram sample of a radioisotope decays to 12.5 grams in 14.4 seconds. What is
the half-life of this isotope?

Answer 1

Answer:

Half life = 7.2 seconds

Explanation:

$from \: decay \: equation \\ 2.303 log( \frac{n.}{nt} ) = kt \\ 2.303 log( \frac{50}{12.5} ) = k \times 14.4 \\ k = \frac{2.303 log( \frac{50}{12.5} )}{14.4} \\ k = 0.096288 {s}^{ - 1} \\ since \: half \: life = \frac{ ln(2) }{k} \\ half \: life = \frac{ ln(2) }{0.096288} \\ half \: life = 7.2 \: seconds$

Answer 2

14.2 because basically you just divide it by 2 which would be half of it

That will work with all of those problems

So if it’s is a quarter of an isotope you’d divide by 4