One radioisotope used for the dating of rocks and fossils


A) one B) two C) three D) four E) five Answer: C Topic: Concept 26.2 Skill: Application (a) 14C / C14 / carbon-14 40K / K40 / potassium-40 1) The original concentration of the radioisotope must be established/estimated in the rock or fossil sample; 2) The rate of decay called the half-life of the isotope must be known, that is, the time it takes for half of the radioactive isotope in a sample to decay into its stable daughter isotope form.3) In radiocarbon dating concentration of the surviving 14C in the fossil is measured; 4) In potassium-argon dating ratio of the radioactive isotope, 40K to its stable daughter isotope, 40Ar atoms are measured; In a population of 10,000 newborn babies, the expected proportion of babies having the disease is 4/ 10,000 = 0.0004, which is q.those that form during chemical reactions without breaking down).The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.

Explore this link for additional information on the topics covered in this lesson: This activity will help students to have a better understanding of the basic principles used to determine the age of rocks and fossils. Objectives of this activity are: 1) To have students determine relative age of a geologically complex area.

Carbon dating is used to determine the age of biological artifacts up to 50,000 years old.

This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils (like those of the dinosaurs alleged to be millions of years old).

Perhaps the most widely used evidence for the Theory of Evolution through Natural Selection is the fossil record.

The fossil record may be incomplete and may never fully completed, but there are still many clues to evolution and how it happens within the fossil record.

Levels of carbon-14 become difficult to measure and compare after about 50,000 years (between 8 and 9 half lives; where 1% of the original carbon-14 would remain undecayed).

The question should be whether or not carbon-14 can be used to date any artifacts at all? There are a few categories of artifacts that can be dated using carbon-14; however, they cannot be more 50,000 years old.

If the half-life of carbon-14 is about 5,730 years, then a fossil that has one-eighth the normal proportion of carbon-14 to carbon-12 is probably ________ years old.

A) 1,400 B) 2,800 C) 11,200 D) 16,800 E) 22,400 Answer: D Topic: Concept 26.2 How many half-lives should have elapsed if 12.5% of the parent isotope remains in a fossil at the time of analysis?

It wasn't until well into the 20th century that enough information had accumulated about the rate of radioactive decay that the age of rocks and fossils in number of years could be determined through radiometric age dating.

This activity on determining age of rocks and fossils is intended for 8th or 9th grade students.

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