# A moon rock collected by a U.S. Apollo mission is estimated to be 3.70 billion years old by uranium/lead dating.?

A moon rock collected by a U.S. Apollo mission is estimated to be 3.70 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass of Pb206 in the rock, if it currently contains 1.230 g of U238? The half-life of U238 is 4.47×109 years.

Pb206 mass:

Relevance
• It happened Naturally

So if there was any Lead involved, it would have been a remnant of a Supernova

Kind of Figures in the Scheme of things and it was once part of Earth

So things are the way they are Source(s): Who needed a Nuke when there was Thiea ?
• It isn't assumed that the rock contained no lead. The sample is known to have contained no lead. They don't just grab any old rock.

Source(s): [n] = 10ⁿ
• Anonymous
5 months ago

• half-life of U238 is 4.47×109 years WRONG

perhaps 4.47×10^9 years  ??

3.7 billion = 3.7e9

3.7e9 / 4.47e9 = 0.828, number of half lives

N(t) = N₀(1/2)^(t/th)

1.23 = N₀(1/2)^(0.828)

1.23 = N₀(0.563)

N₀ = 2.18 g

N(t) = N₀(1/2)^(t/th)

N₀ is initial amount

N(t) is the amount remaining after time t

th is the half life time, ie, time for half the amount to decay