Assertion: neptunium's isotope | /r/HasAspect | -lives
Facets:
Source sentences:
text: Since all isotopes of neptunium have half-lives that are many times shorter than the age of the Earth, any primordial neptunium should have decayed by now.
text: All the remaining radioactive isotopes have half-lives that are less than 4.5 days, and the majority of these have half-lives that are less than 50 minutes.