In vanadium there is gradual change from the basic
V2O3 to less basic V2O4 and to amphoteric V2O5 V2O4 dissolves in acids
to give VO
2+ salts Similarly, V2O5 reacts with alkalies as well as acids
to give
43
VO   and
4
VO  respectively The well characterised CrO is basic
but Cr2O3 is amphoteric