Question

How much of a sample remains after five half-lives have occurred?

Answer 1

Answer:

1/32 of the original sample

Explanation:

We have to use the formula

N/No = (1/2)^t/t1/2

N= amount of radioactive sample left after n number of half lives

No= original amount of radioactive sample present

t= time taken for the amount of radioactive samples to reduce to N

t1/2= half-life of the radioactive sample

We have been told that t= five half lives. This implies that t= 5(t1/2)

N/No = (1/2)^5(t1/2)/t1/2

Note that the ratio of radioactive samples left after time (t) is given by N/No. Hence;

N/No= (1/2)^5

N/No = 1/32

Hence the fraction left is 1/32 of the original sample.