Out of following how many oxides are amphoteric in natureMnO,Mn2O,MnO2,Cr2O3,Mn2O7,Mn3O4

MnO2 Higher oxidation states are short of electrons, meaning they can accept lone pairs and functions as Lewis acids,  has the lowest oxidation state, So it is the most basic and finally Mn2O7. So, basically MnO2 is weakly acidic and mildly basic and can some what be classified as amphoteric. Cr2O3,MnO2,Mn3O4 are amphoteric in nature.