Oxides of metal or non-metal can either be acidic, basic, amphoteric or neutral. These acidic or basic oxides can react with water to form acids or bases.
Metal oxides are basic as they form metal hydroxides when reacted with water
Example: Metal Oxide + Water → Metallic Hydroxide
Sodium Oxide (Na2O) Na2O + H2O → 2NaOH
Magnesium Oxide (MgO) MgO + H2O → Mg(OH)2
Zinc Oxide (ZnO) ZnO + H2O → Zn(OH)2
Non-metal oxides are acidic as they form acids when reacted with water
Example: Non-metal Oxide + Water → Acid
Carbon Dioxide (CO2) CO2 + H2O ⇌ H2CO3
Sulfur Trioxide (SO3) SO3 + H2O → H2SO4
Phosphorous Pentoxide (P2O5) P2O5 + 3H2O → 2H3PO4