Ascientist digs up sample of arctic ice that is 458,000 years old. he takes it to his lab and finds that it contains 1.675 grams of krypton-81. if the half-life of krypton-81 is 229,000 years, how much krypton-81 was present when the ice first formed? use the formula n = n0 . the ice originally contained grams of krypton 81.

6.70 g

Explanation:

A common formula for determining the amount of sample remaining in terms of its half-life is

where

t = 458 000 yr

        Calculate n

n = 458 000/229 000

n = 2.000

===============

N = 1.675 g                       Calculate N₀

1.675 = N₀ × 0.2500     Divide by 0.2500 and transpose

N₀ = 1.675/0.2500

N₀ = 6.70 g