600 mL of 0 . 01 M   HCl is mixed with 400 mL of 0 . 01 M   H 2 SO 4 . The pH of the mixture is…

The number of millimoles = $\mathrm{Molarity} \times \mathrm{Volume}$ in $\mathrm{mL}$

$\mathrm{HCl}$ produce one and ${\mathrm{H}}_2{\mathrm{SO}}_4$ produce two ${\mathrm{H}}^{+}$ ions respectively.

Total milimoles of ${\mathrm{H}}^{+}=\left(600\times 0.01\right)+\left(400\times 0.01\times 2\right)=14$
Thus, moles of hydrogen ion:
$\Rightarrow \left[{\mathrm{H}}^{+}\right]=\frac{14}{1000}=14\times {10}^{-3}$
$$\begin{gathered} \Rightarrow \mathrm{pH} = -\log \left[{\mathrm{H}}^{+}\right] \\ =-\log [14 \times {10}^{-3}] \end{gathered}$$

$\Rightarrow \mathrm{pH}=3-\log 14$

$=1.86$

$=186\times {10}^{-2}$