Assertion: nitrogen's form | /r/HasProperty | stored under water
Facets:
value: to prevent it
type: PURPOSE
Source sentences:
text: Phosphorus exists in a variety of physical modifications, or allotropic forms, including the familiar white, highly reactive form that must be stored under water to prevent it from igniting in the air; a much less reactive red or violet form; and a black modification that, although least known, appears to be the most stable of all.