A 5.1 wt % solution of H₂SO₄ has a density 1.03 g cm^-3 at 298 K. The mole fraction and molarity of the acid, respectively, are

$94.9 \mathrm{gm} \mathrm{of} \mathrm{water} =\frac{94.9}{18}=5.27 \mathrm{moles}$
Moles of H₂SO₄ $=\frac{5.1}{98}=0.052$
Mole fraction of acid$=\frac{0.052}{5.27+0.052}=9.78\times {10}^{-3}$
Molarity of the acid$=\frac{100}{1.03}{\mathrm{cm}}^3$contain 0.052 moles of H₂SO₄ 
$=1000{\mathrm{cm}}^3\text{ contain }\frac{1000\times 0.052\times 1.03}{100}=\mathbf{0}\mathbf{.}\mathbf{535}.$