If a rock sample contains uranium and lead, but no lead-204 is present, then
A) all the lead is radiogenic.
B) all the lead is primordial.
C) both radiogenic and primordial lead are present.
D) neither radiologic nor primordial lead is present.

Question

Quizplus · Accepted Answer

If no lead-204 is present in a rock sample containing uranium and lead, all the lead must be radiogenic. Lead-204 is a non-radiogenic (primordial) isotope of lead, not produced by radioactive decay. The absence of lead-204 suggests that the lead present has been generated through the radioactive decay of uranium, making it radiogenic.

If a Rock Sample Contains Uranium and Lead, but No