Question

90Sr is one of the harmful radionuclides resulting from nuclear fission explosions. It decays by a first-order process with a half-life of 28 years. How many years would it take for 99.99% of a given sample released in the atmosphere to disintegrate? Answer in units of years.

i solved for k and got .02476 from the half life equation for first order and then i know i need to use this equation: ln(No/N) = kt but i don't know what to use for No/N...

Answer 1

I would just make up a convenient number, like 100 for example for No. That would make 100 x 0.9999 = 99.99 to disappear which leaves 100-99.99 = 0.01 = N. Check my math

Answer 2

372.12 yrs