why acidic character of E2O3 decrease down the group 15?
Nitrogen, phosphorus, arsenic, antimony, bismuth are elements of group 15.
Acidic character of oxides of this group decreases and basicity increases down the group.
On moving down the group, the atomic size increases, electronegativity decreases and metallic character increases.
All these elements form two types of oxides: E2O3 and E2O5.
The oxide in the higher oxidation state of the elements is more acidic than that of lower oxidation state.
Oxides of nitrogen and phosphorus are acidic.
Oxides of As and Sb are amphoteric and Bismuth are basic.