1A) How old is the rock if the mineral biotite from the rock has 100, 000 40K(Po

Question

1A) How old is the rock if the mineral biotite from the rock has 100, 000   40K(Potassium-40) atoms and 100, 000   40Ar(Argon-40) atoms?

1B) What if it had instead 125 40K(Potassium-40) atoms and 875 40Ar(Argon-40) atoms?

4A) Pebbles of an igneous rock are incorporated within a conglomerate. The pebbles yield a radiometric age of 300 million years. What can you say about age of the conglomerate based on this data?

4B) the same is intruded by a dyke that yields a radiometric age of 200 million years. What can you now say about the possible age range of the conglomerate?

5) would it be possible to use 14C (Carbon-14) age dating to estimate the age of the rock containing carbon from the time of the dinosours? Explain.

6) How many half-lives are required to yield a mineral with 625 atoms of 238U (Uranium-238) and 19, 375 atoms of 206Pb(Plumbum-206)? (The half-life for 238U to 206Pb decay is 0.71x10^9 years)

7) calculate the age of the rock containing the following atoms of radioactive parent element A: 1,125,000 atoms. Stable daughter element B: 34, 875, 000 atoms. The half-live element A is 6.25 million years. What is the absolute age of the rock containing these parent and daughter elements?

8) A bone is recently discovered from a site in eastern Africa. Radiocarbon dating suggest that the bone contains 12.5% of the original amount of 14C (carbon-14). How old is the bone? (half-life of 14C = 5, 730 years). Is it possible that the bone belongs to a dinosaur?

Explanation / Answer

ANSWER1(A):- 1/2 of the original parent has decayed, thus one half- life has passed, and the rock is 1.3 billion = 1300 million years old

ANSWER1(B):-All of the daughter was once parent, so 125/(125+875) = 125/1000 = 0.125 gives 12.5% of the parent remaining. Thus 3 half - lives have passed, and the rock is 3(1.3 billion) = 3.9 billion years old = 3900 million years old.

ANSWER 4(A):-The conglomerate is younger than the pebbles, so it

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