Concentrated nitric acid is labelled as 75% by  mass. The volume in mL of the solution which contains 30 g of nitric acid is ___________. (Given : Density of nitric acid solution is 1.25 g/mL)

% w/w of HNO₃ = 75%
means 100 gm of solution containing 75 g of HNO₃
$\mathrm{\&}{\left(\frac{\mathrm{gm}}{{\mathrm{m}}_1}\right)}_{\text{solution }}=1.25=\frac{100\mathrm{gm}}{\mathrm{V}}$
${\mathrm{V}}_{\mathrm{ml}} \text{of }100 \mathrm{gm} \text{solution}=\frac{100}{1.25}\mathrm{ml}$
$\because 75 \mathrm{gm} \text{of }{\mathrm{HNO}}_3 \text{present in }\frac{100}{1.25}\mathrm{ml} \text{solution}$
$\therefore 30 \mathrm{gm} \text{of }{\mathrm{HNO}}_{3 }\text{present in}$
$\frac{100}{1.25\times 75}\times 30=32 \mathrm{ml} \text{solution}$