Sodium-24 has a half life of 15 hours. how much sodium-24 will remain in an 18.0 g sample after 60 hours

Hey there!

A half-life means after a certain amount of time, half of that substance will be gone/changed after that time.

60 hours is 4 half lives because 60 ÷ 15 = 4.

So, the 18g sample will be divided in half 4 times.

18 ÷ 2 = 9

9 ÷ 2 = 4.5

4.5 ÷ 2 = 2.25

2.25 ÷ 2 = 1.125

There will he 1.125g of sodium-24 left after 60 hours.

Hope this helps!