Sulphuric acid is more acidic than nitric acid. Sulphuric acid has a pKa of -2.0, while nitric acid has a pKa of -1.4. This means that sulphuric acid completely dissociates in water, while nitric acid only partially dissociates. As a result, sulphuric acid has a higher concentration of hydrogen ions (H+) than nitric acid, making it more acidic.