Tutoring chemistry, the concept of acid strength is important. The tutor explains why nitric acid is more acidic that nitrous.

Nitric acid (HNO₃) and nitrous acid (HNO₂) both have N as the central atom, and share the structure H-O-N….However, nitric acid has an extra oxygen on the other side of N, which causes more electron drain from the N atom. The N atom, in turn, pulls electron density from the O between it and the H. With less electron availability, the O adjacent to H in HNO₃ can less effectively attract H⁺, so loses it more readily than does HNO₂.

Source:

Mortimer, Charles E. Chemistry, sixth ed. Belmont: Wadsworth, 1986.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.