Question

Cobalt-60, with a half-life of 5.0 days, is used in cancer radiation treatments. A hospital purchases a 30.0g supply of it and stores it on a shelf in a closet. The next time a hospital worker grabs the bottle, though, they find that it only contains 3.75 g remaining! Assuming the bottle had never been opened, how long was the bottle sitting on the shelf before the worked grabbed it?

Answer 1

Bottle is sitting on the shelf for 15 days.

Step-by-step explanation:

Given data:

Co-60 half life = 5 days

Total amount = 30.0 g

Amount left = 3.75 g

Time taken = ?

Solution:

AT time zero = 30 g

AT first half life= 30g /2 = 15 g

At 2nd half life = 15 g/ 2 = 7.5 g

At 3rd half life = 7.5 g/2 = 3.75 g

Now we will calculate the sitting time of bottle.

Half life = Time taken / number of half lives

3× 5 days = time taken

Time taken = 15 days

Bottle is sitting on the shelf for 15 days.