1.) Researchers from the Smithsonian Museum of Natural History retrieved samples
ID: 162678 • Letter: 1
Question
1.) Researchers from the Smithsonian Museum of Natural History retrieved samples of fossil plants from an ancient lake bed in Patagonia. They used Carbon-14 radiometric dating to estimate the age of these plant fossils (the half life of Carbon-14 is 5730 years). They determined that these fossils are about 14,325 years old. Approximately what percentage of the parent isotope (C14) remains in these fossils?
2.) A paleontologist is radiometrically dating three rocks from three different sites using the Potassium-Argon "clock", which has a half life of 1.25 billion years. The data she has obtained is shown in the table below. Based upon these data, which rock is the oldest?
Rock being test
a. rock a
b. rock b
c. rock c
d. you cannot determine this from the info given
3.) Which of the following statements about natural selection is most accurate?
a 50% (1 half life)Explanation / Answer
Ans 1 D 18.75% (2.5 half lives)
half lifr is the time taken by the radioactive element to become half of its original quantity. Here the estimated time is 14325 yrs which is approximately 2.5 times the half life of C14 carbon isotope. So now the amount of carbon left in the fossil is 18.75%.
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