Chemistry - Concentration Terms Question with Solution | TestHub

$25\mathrm{mL}$ of $\mathrm{HCl}$ solution requires $30\mathrm{mL}$ of $0.1\mathrm{M}$ ${\mathrm{Na}}_2{\mathrm{CO}}_3$ solution. $$\begin{array}{l}\because {\mathrm{N}}_1{\mathrm{V}}_1={\mathrm{N}}_2{\mathrm{V}}_2\\ \therefore 25\times {\mathrm{N}}_1=30\times 0.2(0.1\mathrm{M}{\mathrm{Na}}_2{\mathrm{CO}}_3=0.2\mathrm{N}\\ {\mathrm{Na}}_2{\mathrm{CO}}_3)\\ {\mathrm{N}}_1=\frac{6}{25}=0.24\mathrm{N}\end{array}$$ Now, HCl solution is titrated with $\mathrm{NaOH}$ solution. $$\begin{array}{l}{\mathrm{M}}_1{\mathrm{V}}_1={\mathrm{M}}_2{\mathrm{V}}_2;0.24\mathrm{NHCl}=0.24\mathrm{M}\mathrm{HCl}\\ \therefore \mathrm{V}\times 0.24\times 1=30\times 0.2\times 1\Rightarrow \mathrm{V}=25\mathrm{mL}\end{array}$$