In case of transition metal oxides, the oxides with metals in lower oxidation states are basic in nature. O.S. of Mn in Mn2O7=+7; V in V2O3=+3; V in V2O5=+5; Cr in CrO=+2; Cr in Cr2O3=+3
Thus in V2O3, CrO and Cr2O3 transition metal ion is in lower oxidation state but Cr2O3 is amphoteric in nature. Hence V2O3 and CrO are basic in nature.