Why are isotopes with short half-lives not useful for dating very old rocks? -because not enough of the parent isotope remains to measure accurately
-because not enough of the daughter product has formed to be detectable
-because neither the parent isotope nor the daughter product will be detectable
-because very old rocks would never have contained these isotopes

The radioactive isotopes within these brains typically record the ages of the grains-not the time when the sedimentary rock was formed, making it difficult to date using radiometric dating. The half-life of U-235 is 704 million years.

Explanation:

hope this helps but if i'm wrong then i'm sorry..

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Explanation:

Very old rocks would be been formed before said isotopes with short half-lives. We're thinking of a very long geological time. The original rock might be rock C, then years and years later rock Y would be measured. Y can't match C since there's too much unknowns in between.

the dissolution of polymer can be thermodynamically described in 2 steps.

the answer is 0.8m.

by: nicholas