Correct Answer - 3
As a general rule,only nonmetallic oxides are acidic but oxides of some metals in higher oxidation states also have acidic character.For example :
`SnO_(2)+H_(2)OrarrH_(2)SnO_(3)`
`Mn_(2)O_(7)+H_(2)Orarr2HMnO_(4)`
`CrO_(3)+H_(2)OrarrH_(2)CrO_(4)`
In vanadium there is a gradual change from the basic `V_(2)O_(3)` to less basic `V_(2)O_(4)` and to amphoteric (through mainly acidic) `V_(2)O_(5)`
in general.metallic oxides are basic.
