Assouplir belong to the 2
nd group. Assouplir is a common french verb.
Assouplir is conjugated the same way that verbs that end in :
-ir
Assouplir is conjugated with
auxiliary avoir.
Assouplir verb is
direct transitive.
French verb assouplir can be conjugated in the reflexive form:
S'assouplir
Assouplir verb is a direct transitive verb, so passive voice can be used.