Assertion: neptunium's isotope | /r/HasProperty | longest-lived
Facets:
value: longest
type: DEGREE
Source sentences:
text: Its longest-lived isotope is 237Np with a half-life of 2.14 million years followed by 236Np with a half-life of 154,000 years and 235Np with a half-life of 396.1 days.