Question

680 g of sodium 24 was placed in a container to decay if there is now 85 g of sodium 24 left how long has the sodium been decaying

Answer 1

Answer:44.7 hours.

Step-by-step explanation:

The time taken for the radioactivity of a specified isotope to fall to half its original value is called half life of that radioactive material.

Half life of sodium-24 is
`14.9` hours.

Initial amount of sodium-24 is
`680g`

In
`14.9` hours,the quantity falls to
`(680)/(2)=340g`

In another
`14.9` hours,the quantity falls to
`(340)/(2)=170g`

In another
`14.9` hours,the quantity falls to
`(170)/(2)=85g`

So,it takes
`14.9+14.9+14.9=44.7` hours for the quantity to become
`85g`.