Oxides of elements placed in the centre of the periodic table are amphoteric or neutral (e.g. CO, NO, N2O).SiO2 is slightly acidic.
Types of oxides
1) Acidic oxide: Oxides of non-metals.
2) Basic oxides: These are oxides of metals
3) Amphoteric oxides: Oxides shows both basic and acidic properties.
4) Neutral oxides: Shows neither acidic nor basic properties