Question

Iodine-131 has a half-life of 8 days. How much would be left of an original 40 g sample after 40 days?

a) 32g
b) 8g
c) 131g
d) 1.25g
e) 0.8g​

Answer 1

Answer: 1.25g

Explanation:

Got it rght on an assignment

Answer 2

d) 1.25 g

Explanation:

If it has a half life of 40 days, there will be 5 half-lives in that span of time so if you divide 40 by 2, 5 times or just
`(40)/(2^(5) )`, it will equal 1.25.

`(40)/(2)=20\\`

`(20)/(2) =10`

`(10)/(2) =5`

`(5)/(2) =2.5\\`

`(2.5)/(2) =1.25`