Here's why:

* Strength of the acid: Acidity is determined by the ability of an acid to donate protons (H+ ions). Sulfuric acid is a stronger acid because it readily donates both of its protons, while nitric acid only donates one.

* Electronegativity: The sulfur atom in sulfuric acid is more electronegative than the nitrogen atom in nitric acid. This means sulfur attracts electrons more strongly, leading to a more polarized O-H bond and a greater tendency to release protons.

* Resonance stabilization: The sulfate ion (SO₄²⁻) is more resonance stabilized than the nitrate ion (NO₃⁻). This stabilization makes it easier for sulfuric acid to lose its protons.

In summary: Sulfuric acid has a higher tendency to donate protons, making it a stronger acid than nitric acid.