Posted by jezebel on .
Iodine131 has a half life of eight days. What mass of iodine131 would remain from a 20g sample after 32 days?

chemistry 
DrBob222,
k = 0.693/t_{1/2}
ln(No/N) = kt
No = 20g
N = solve for this
k from above.
t = 32 days.