Which statement best explains why dating geologic materials from the Quarternary Period uses a different radioactive isotope than for materials from the cambrian Period?

a. all rocks contain radioactive substances.

b. some isotopes decay faster than others.

c. not all isotopes form stable decay products

d. the decay of atoms occurs as a random event

i think it's b..

I think you are correct.

Statements b,c,and d are correct but only b answers the question.

thanks

You are correct! Option b, "some isotopes decay faster than others," is the best explanation for why dating geologic materials from the Quaternary Period uses a different radioactive isotope than materials from the Cambrian Period.

To understand why this is the case, let's dive deeper into the concept of radioactive decay and the dating of geologic materials.

Radioactive decay is a spontaneous process in which the atomic nucleus of an unstable isotope releases particles or energy to become more stable. Different isotopes have different rates of decay, meaning that they decay at different speeds. This is determined by the half-life of the isotope, which is the time it takes for half of the original number of radioactive atoms to decay.

In geological dating, scientists use the principle of radioactive decay to determine the age of rocks and minerals. By measuring the amounts of a radioactive isotope and its decay product(s) in a sample, scientists can calculate how much time has passed since the rock formed.

The choice of isotope used for dating depends on the age range of the material being studied. The Quaternary Period encompasses the most recent 2.6 million years, whereas the Cambrian Period spans approximately 541 to 485.4 million years ago. Since these periods have vastly different ages, it is necessary to use different isotopes with appropriate half-lives to accurately date materials from each period.

Materials from the Quaternary Period, being relatively young, require isotopes with shorter half-lives. For example, Carbon-14 (C-14), which has a half-life of about 5730 years, is commonly used for dating objects up to about 50,000 years old.

In contrast, materials from the Cambrian Period require isotopes with longer half-lives because the time scale involved is much greater. For dating ancient rocks, uranium-based isotopes like Uranium-238 (U-238) or Potassium-40 (K-40), with half-lives of 4.5 billion and 1.25 billion years, respectively, are commonly used.

Therefore, option b is the best explanation because it recognizes that different isotopes decay at different rates, which is why different isotopes are used for dating materials from different geological periods.