Question

The half-life of Iodine-131 is approximately 8 days. Find the amount of Iodine-131 left from a 42 gram sample after 16 days.

1) 0.0006 grams

2) 21 grams

3) 10.5 grams

4) 34 grams

Answer 1

Explanation:

The formula for this is

`N=N_0(.5)^{(t)/(H)` where

N is the amount of the element left after a certain amount of time (for us it is measured in days),

N₀ is the initial amount of the element in grams,

t is the number of days gone by, and

H is the half life of the element. Filling in:

`N=42(.5)^{(16)/(8)` which simplifies a bit to

`N=42(.5)^2` and a bit more to

N = 42(.25) which gives us a remaining amount of

N = 10.5