When 100 mL of 0. 1 M KNO₃ and 400 mL of 0.2 M HCI and 500 mL of 0.3 M H₂SO₄ are mixed, then in the resulting solution

$$\begin{gathered} \begin{array}{l}{\mathrm{KNO}}_3 + \mathrm{HCl} + {\mathrm{H}}_2{\mathrm{SO}}_4\\ \left(\begin{array}{c}100\times 0.1\\ =10\mathrm{mmol}\end{array}\right)\left(\begin{array}{c}400\times 0.2\\ =80\mathrm{mmol}\end{array}\right)\left(\begin{array}{c}500\times 0.3\\ =150\mathrm{mmol}\end{array}\right)\end{array} \\ \mathrm{Total} \mathrm{volume} = 100+400+500=1000 \mathrm{mL} \end{gathered}$$

$\begin{array}{l}{\mathrm{M}}_{\mathrm{K}}\oplus =\frac{10}{1000}=0.01\mathrm{M}\\ {\mathrm{M}}_{{\mathrm{SO}}_4^{-2}}=\frac{150}{1000}=0.15\mathrm{M}\\ {\mathrm{M}}_{\mathrm{H}}\oplus =\frac{80+2\times 150}{1000}=0.38\mathrm{M}\\ {\mathrm{M}}_{{\mathrm{NO}}_3}^{\ominus }=\frac{10}{1000}=0.01\mathrm{M}\\ {\mathrm{M}}_{{\mathrm{Cl}}^{\ominus }}=\frac{80}{1000}=0.08\mathrm{M}\end{array}$