pH of Strong Acids

Strong acid, one proton: [H₃O⁺] = c, then pH = −log c. 0.01 M HCl: pH 2.

Two protons (H₂SO₄): [H₃O⁺] = 2c first. 0.005 M H₂SO₄: [H₃O⁺] = 0.01 M, pH 2.

Not a power of ten? Use log: 0.002 M HCl has pH 2.70. Give pH to two decimals.