Which oxide of a group 15 element is the most acidic?
Acidity of group 15 oxides increases with oxidation state and decreases down the group. N₂O₅ (N in +5) is the most acidic, forming HNO₃, unlike P₂O₅, As₂O₅, or Sb₂O₅.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Genesis of Periodic Classification - Dobereiner Newlands Mendeleev