Radium-226 is a common isotope on Earth,but has a half-life of about 1600 years.Given that Earth is some 5 billions years old,why is there any radium at all?
A)Radium-226 is one of several self-transmutating isotopes of the elements of the periodic table and is able to replenish itself so that it is never depleted.
B)Radium-226 and Radium-218 undergo a series of transmutation reactions of alpha and beta decay to repeatedly become one another approximately every 1600 years.
C)Radium-226 is a "daughter" isotope and the result of the radioactive decay of uranium.
D)Radium-226 and Astatine-218 are converted back and forth via transmutation to one another at each of their respective half-life cycles.

Question

Quizplus · Accepted Answer

Radium-226 is a decay product of the decay chain of uranium. As uranium decays, it eventually reaches a stable isotope of lead-206, but along the way, it produces other radioactive isotopes such as radium-226. Despite the relatively short half-life of radium-226, there has been enough time since the formation of Earth for it to accumulate through the decay of uranium.

Radium-226 Is a Common Isotope on Earth,but Has a Half-Life