Question

Why acidic character of oxides decrease down the group?

Answer 1

Acidic character of oxides decrease down the group:
The acidic character of the oxides "decreases down the group" because the electronegativity decreases down the group. Electronegativity is the property of the element to attract electron pairs.
When the metal is more electro-positive, it has more basic oxide in nature. When the non-metal is more electro-negative, it has more acidic oxide in nature. The electronegativity decreases down the group because the "distance between the nucleus and the valence shell electron increases".