Explain the nature of oxide compounds of group-$15$ elements.

All the elements of group-$15$ form two types of oxides: $E_{2}O_{3}$ and $E_{2}O_{5}$.
The oxide in the higher oxidation state of the element is more acidic than that of the lower oxidation state.
The acidic character decreases down the group.
The oxides of the type $E_{2}O_{3}$ of nitrogen and phosphorus are purely acidic,those of arsenic and antimony are amphoteric,and those of bismuth are basic.
The acidic strength of the trioxides and pentoxides decreases with the decrease in the electronegativity of the central atom.
Acidic Strength of trioxide: $N_{2}O_{3} > P_{2}O_{3} > As_{2}O_{3}$
Acidic Strength of pentoxide: $N_{2}O_{5} > P_{2}O_{5} > As_{2}O_{5}$