What concentration in percent is 0.01M sulfuric acid?

Consider 1 L of the sulfuric acid.
No. of moles of H₂SO₄ in 1 L of the sulfuric acid = (0.01 mol/L) × (1 L) = 0.01 mol

Molar mass of H₂SO₄ = (1×2 + 32 + 16×4) g/mol = 98 g/mol
Mass of H₂SO₄ in 1 L of the sulfuric acid = (0.01 mol) × (98 g/mol) = 0.98 g

As the solution is very dilute, Volume of water used ≈ Volume of solution = 1 L = 1000 mL
Density of water = 1 g/mL
Mass of water in 1 L of the sulfuric acid = (1000 mL) × (1 g/mL) = 1000 g
Hence, Mass of the solution = (1000 + 0.98) g = 1000.98 g ≈ 1000 g

Concentration in percent (by mass) = (0.98/1000) × 100% = 0.098%