Question

The half-life of Iodine-131 is approximately 8 days. What is the amount of Iodine-131 left from a 35 gram sample after 32 days?

Answer 1

`2.2` grams

Explanation:

32 days means 4 half lives since one half life is 8 days.
That means it will be halved 4 times... so the ratio between the initial amount and the amount after 32 days will be `0.5^4`.

`35 times 0.5^4 = 2.1875`

There will be `2.2` grams left.