The half-life of sodium-24 is 15 hours, how much of the 16 g remains after
60 hours?

After 60 hours 1 g is left.

Explanation:

Given data:

Half life of sodium = 15 hours

Total amount = 16 g

Amount remain after 60 hours = ?

Solution:

First of all we will calculate the number of half lives:

Number of half lives = Time elapsed / half life

Number of half lives = 60 hours / 15 hours

Number of half lives = 4

Amount left:

At time zero = 16 g

At first half life = 16 g/2= 8 g

At 2nd half life = 8 g/2 = 4 g

At 3rd half life = 4 g/2 = 2 g

At 4th half life = 2 g/2 = 1 g

After 60 hours 1 g is left.