n(H2SO4)=0.5L×1mol/L=0.5mol∴m(H2SO4)=0.5mol×98g/mol=49g ∴v(H2SO4)=49g/1.8g/cm^3÷98%=250/9cm^3≈27.8cm^3∴需量取98%浓硫酸27.8ml
