32P is a radioactive isotope with a half-life of 14.3 days. If you currently have 48.1 g of 32P, how much 32P was present 3.00 days ago?

Answer 1

Using half-life, calculate rate constant, k, from the following
k = 0.693/t_{1/2, then substitute k into the following
ln(No/N) = kt
No = unknown
N = 48.1 g.
k from above.
t = 3 days.}