The volume of concentrated hydrochloric acid (density  $:1.20 \mathrm{g}{\mathrm{mL}}^{-1}$) containing 36.5 mass per cent of HCI required for preparing 2 L of 0.1 M hydrochloric acid solution is about

In 100 g of $\mathrm{HCl}$ solution, the amount of $\mathrm{HCl}$ is $n=\frac{m}{M}=\frac{36.5\mathrm{g}}{36.5\mathrm{g}{\mathrm{mol}}^{-1}}=1.0\mathrm{mol}$

Volume of 100 g of $\mathrm{HCl}$ solution $V=\frac{m}{\rho }=\frac{100\mathrm{g}}{1.20\mathrm{g}{\mathrm{mL}}^{-1}}=83.3\mathrm{mL}$

The amount of $\mathrm{HCl}$ in 2 L of0.1 M $\mathrm{HCl}$ solution, $n_2=MV=\left(0.1{\mathrm{molL}}^{-1}\right)\left(2\mathrm{L}\right)=0.2\mathrm{mol}$

Hence, the volume of solution containing 0.2mo] $\mathrm{HCl}$ is $V=\left(\frac{83.3\mathrm{mL}}{1.0\mathrm{mol}}\right)\left(0.2\mathrm{mol}\right)=16.66\mathrm{mL}$