34. Using Eq. 43-14 and Eq. 43-17 (and the fact that mass is proportional to the number of atoms), the amount decayed is |"m| = m|t =16.0h - m|t =14.0h f i i f = m0(1 - e-t ln 2/T1/2) - m0(1 - e-t ln 2/T1/2) f i = m0(e-t ln 2/T1/2 - e-t ln 2/T1/2)
= (5.50 g) e-(16.0h/12.7h)ln2 - e-(14.0h/12.7h)ln2 = 0.256 g .