the oldest rocks on earth are believed to be several billion years old. which of the following radioisotopes…
the oldest rocks on earth are believed to be several billion years old. which of the following radioisotopes could be used to determine or confirm the age of those rocks?\n| radioisotope | half - life |\n|--|--| \n| samarium - 147 | 106 billion years |\n| uranium - 238 | 4.5 billion years |\n| uranium - 235 | 704 million years |\n| carbon - 14 | 5,730 years |\n| radium - 226 | 1,600 years |\n| americium - 241 | 432 years |\nyou can select more than one radioisotope. support your choice with reasoning about half - life.
Answer
Brief Explanations:
Radiometric dating relies on the predictable decay of radioactive isotopes. To accurately date materials that are several billion years old, the chosen radioisotope must have a half-life that is long enough for a measurable amount of the parent isotope to still be present after billions of years. Isotopes with very short half-lives (like Carbon-14, Radium-226, Americium-241) would have decayed almost completely over such a vast timescale, making them unsuitable. Isotopes with half-lives on the order of millions or billions of years are appropriate. Uranium-238 has a half-life (4.5 billion years) very close to the age of the Earth, making it ideal. Uranium-235 (704 million years) and Samarium-147 (106 billion years) also have sufficiently long half-lives to be useful for dating rocks of this age.
Answer:
Samarium-147 (106 billion years) Uranium-238 (4.5 billion years) Uranium-235 (704 million years)