How many grams of sodium-24 will remain at the end of 4 half-lives?

Answer 1

Suppose you start with 1000 g of sodium-24 .

t = 0.0 m = 1000 g

t = 1 half-life m = 500 g

t = 2 half-lives m = 250 g

t = 3 half-lives m = 125 g

t = 4 half-lives m = 62.5 g

Answer 2

At the end of 4 half-lives, only 1/16th (1/2^4) of the original amount of sodium-24 will remain. If you start with 100 grams, at the end of 4 half-lives, you will have 6.25 grams remaining (100 grams * 1/2^4).