Assertion: protactinium's isotope | /r/HasProperty | reduced to 2.8×10−12%
Facets:
Source sentences:
text: All the isotopes which have half-lives less than 100 million years have been reduced to 2.8×10−12% or less of whatever original amounts were created and captured by Earth's accretion; they are of trace quantity today, or have decayed away altogether.