(a) Metal oxides are basic in nature. Acids react with metal oxides to form salt and water.
Example: Dilute sulphuric acid reacts with calcium oxide to form calcium sulphate and water.
CaO(s)+H2SO4(aq)→CaSO4(aq)+H2O(l)
Salt Water
(b) Yes, there are a few oxides of amphoteric metals such as zinc and aluminium which react with acids as well as bases too.
Reaction with acid:
Al2O3(s)+6HCl(aq)→2AlCl3(aq)+3H2O(l)
Acid
Reaction with base:
Al2O3(s)+2NaOH(aq)→2NaAlO2(aq)+H2O(l)
Base