The volume of 96% by mass ${\mathrm{H}}_2{\mathrm{SO}}_4$ (density 1.83 g ml ) required to prepare 2 litres of 3M ${\mathrm{H}}_2{\mathrm{SO}}_4$ solution is

${\mathrm{M}}_1{\mathrm{V}}_1={\mathrm{M}}_2{\mathrm{V}}_2$

${\mathrm{M}}_1\times {\mathrm{V}}_1=3\times 2$

$\text{but }{\mathrm{M}}_1=\frac{\mathrm{\%}(\mathrm{w}/\mathrm{w})\times \mathrm{d}\times 10}{\text{Mwt of solute}}=\frac{96\times 1.83\times 10}{98}$

${\mathrm{M}}_1=17.9\mathrm{M}$

$\therefore 17.9\times {\mathrm{V}}_1=3\times 2$

${\mathrm{V}}_1=\frac{6}{17.9}=0.3352 \text{litres}$

$=335.2\mathrm{ml}$