# Earth Science

posted by
**Donna** on
.

If you started with 100 grams of Potassium-40 how much would reamin Potassium-40 after 3.9 x 10 to the 9th years?

posted by
**Donna** on
.

If you started with 100 grams of Potassium-40 how much would reamin Potassium-40 after 3.9 x 10 to the 9th years?