5/3if 87.5 percent of a sample of pure 131 i decays in 24 days, what is the half-life of 131 i?

Answer : The half-life of iodine is, 8 days.

Explanation :

First we have to calculate the rate constant.

Expression for rate law for first order kinetics is given by:

where,

k = rate constant  = ?

t = time passed by the sample  = 24 days

a = let initial amount of the reactant  = 100 g

a - x = amount left after decay process = 100 - 87.5 = 12.5 g

Now put all the given values in above equation, we get

Now we have to calculate the rate constant, we use the formula :

Therefore, the half-life of iodine is, 8 days.

c) should be the answer.