Acheter belong to the 1st
group. Acheter is a very common french verb.
Acheter is conjugated the same way that verbs that end in : -eter
Acheter is conjugated with auxiliary avoir
Acheter verb is
direct transitive, intransitive.
French verb acheter can be conjugated in the reflexive form: S'acheter
verb is a direct transitive verb, so passive voice can be used.