Advanced Placement (AP): 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?

There is 8.806 × 10^10 hectares in 340 million square miles....

A rock sample contains 7.5 g of Californium-249

RDS468

18.03.2022

Rock is 1080 days old

Explanation:

Total Mass = 52.5 grams + 7.5 grams = 60 grams

As we know

$\frac{7.5}{60} = \frac{60* (\frac{1}{2} ) (\frac{t}{360d})}{60}$

$0.125 = 0.5* (\frac{t}{360d})$

Taking log on both sides we get –

Log $(0.125) = \frac{t}{360}$ log (0.5)

$\frac{-0.903}{-0.301 } = \frac{t}{360}$

t = 3 * 360

t = 1080

1080 days

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