Question

The half-life of Radium-224 is
3.66 days. What was the original
mass of this radioactive isotope if
1.2 mg remains after 10.98 days?

Answer 1

half-life equation:

A(t) = A0 * (1/2)^(t/h)

where A0 is the original amount, t is the total time elapsed (10.98 days), h is the half-life (3.66 days), and A(t) is the final amount (1.2 mg). plug in the appropriate quantities into the equation and solve for A0.