Raréfier belong to the 1
st group.
Raréfier is conjugated the same way that verbs that end in :
-ier
Raréfier is conjugated with
auxiliary avoir.
Raréfier verb is
direct transitive.
French verb raréfier can be conjugated in the reflexive form:
Se raréfier
Raréfier verb is a direct transitive verb, so passive voice can be used.