Question

If a 1000g sample of Au-198 is held for a little over 5.4 days, how much of the sample will remain?

Answer 1

$\dfrac{5.4days}{2.7days} =$ 2 half-lifes

$\implies$ $(\dfrac{1}{2})^2 = \dfrac{1}{4}$

$\dfrac{1}{4}x1000g = 250g$ will remain