Question

A rock sample contains 7.5 g of Californium-249 and 52.5 g of the daughter isotope. If the half life of Californium-249 is 360 days, how old is the rock?

Answer 1

Rock is
`1080` days old

Step-by-step explanation:

Total Mass =
`52.5` grams
`+ 7.5` grams
`= 60` grams

As we know

`(7.5)/(60) = (60* ((1)/(2) ) ((t)/(360d)))/(60)`

`0.125 = 0.5* ((t)/(360d))`

Taking log on both sides we get –

Log
`(0.125) = (t)/(360)` log
`(0.5)`

`(-0.903)/(-0.301 ) = (t)/(360)`

`t = 3 * 360`

`t = 1080`

`1080` days