Assertion: osmium's isotope | /r/HasProperty | reported
Facets:
Source sentences:
text: Twelve isotopes with mass numbers ranging from 263 to 277 (with the exceptions of 272, 274, and 276) have been reported, four of which—hassium-265, -267, -269, and -277—have known metastable states, although that of hassium-277 is unconfirmed.