The half-life of oxygen-15 is 124 s. If a sample of oxygen-15 has an activity of 4800 Bq, how many minutes will elapse before it has an activity of 600 Bq?

Answer 1

k = 0.693/t_1/2
Substitute k into the below.

ln(No/N) = kt
No = 4800
N = 600
k from above
Solve for t(which will be in seconds) and convert to minutes.

Answer 2

6.2

Answer 3

24minutes