The density of a monobasic strong acid (Molar mass 24 . 2   g   mol ) is 1 . 21   kg   L…

millimole of $\mathrm{NaOH}=0.24\times 25$
For nuetralisation, equal moles of monoacidic base and monobasic acid must be present:

$\therefore$ millimole of acid $=0.24\times 25$

$\Rightarrow$ mass of acid $=0.24\times 25\times 24.2 \mathrm{g}$

for pure acid,

$\mathrm{V}=\frac{\mathrm{w}}{\mathrm{d}};(\mathrm{d}=1.21 \mathrm{kg}/\mathrm{L}=1.21 \mathrm{g}/\mathrm{ml})$

$\therefore \mathrm{V}=\frac{0.24\times 25\times 24.2}{1.12}\times {10}^{-3}$

$=120\times {10}^{-3}\mathrm{ml}$

$=12\times {10}^{-2}\mathrm{ml}$