Radioactive decay of 40k atoms in an igneous
rock has resulted in a ratio of 25 percent 40k
atoms to 75 percent 40ar and 40ca atoms.
how many years old is this rock?
(1) 0.3 10^9 y (3) 2.6 10^9 y
(2) 1.3 10^9 y (4) 3.9 10^9 y

Radioactive decay of 40K atoms in an igneous rock has resulted in a ratio of 25 percent 40K atoms to 75 percent 40Ar and 40Ca atoms. this rock 2.6 10^9 y years old. The answer is number 3. The rest of teh choices do not answer the question above.

Answer light in color; silica-rich;

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