Posted by Erin on .
If the amount of raidoactive iodine123 in a sample decreases from 0.4 to 0.1 g in 26.2 hours, what is the halflife of iodine123?

Chemistry 
DrBob222,
ln(No/N) = kt
No = 0.4
N = 0.1
t = 26.2 hours.
Solve for k. Then
k = 0.693/t_{1/2}
Solve for t_{1/2>/sub>}