Question

Why metallic oxides are called basic oxides and non-metallic oxides are called acidic oxides ?

Answer 1

Generally Metallic oxides are called Basic Oxide 
example:
Metal + Oxygen -----------> Metal oxide

2Mg +O2 -------->2 MgO

Metal oxide +H2O --------> Metal Hydroxide
MgO +H2O---------> Mg(OH)2
If we test Mg(OH)2 with red litmus paper , it turns blue.
Hence basic in nature.
They are Basic because they react with dilute acids to form salt and water.


All Non metallic oxides are acidic in nature.
NON Metal + Oxygen -----------> Non-Metal oxide

C+O2---------> CO2
CO2+H2O------------>H2CO3 [carbonic acid] we can test with blue litmus paper. It turns red.
Co2 on reacting with water it releases H+ions ... So it is acidic in nature.

Answer 2

Because they reacts with dilute acids to form salt and water

Metaloxide+acid--------->salt and water Cuo+2Hcl------>Cucl2+H2O

HOPE IT IS HELPFUL