A solution is prepared by mixing 0.01 mol each of H₂CO₃, NaHCO₃, Na₂CO₃, and NaOH in 100 mL of water. pH of the resulting solution is _______. [Given: pK_a1 and pK_a2 of H₂CO₃ are 6.37 and 10.32, respectively; log 2 = 0.30]

First acid base reaction between H2CO3 and NaOH takes place.

In the final solution, we have 0.01 mole Na₂CO₃ and 0.02 moles of NaHCO₃.
Here, we have a buffer of NaHCO₃ and Na₂CO₃.
$\begin{array}{l}\therefore \mathrm{pH}={\mathrm{pK}}_{{\mathrm{a}}_2}+\log \frac{\left[\text{ Salt }\right]}{\left[\text{ Acid }\right]}\\ =10.32+\log \frac{\left(\frac{0.01}{0.1}\right)}{\left(\frac{0.02}{0.1}\right)}\\ =10.32+\log \frac{1}{2}\\ =10.32-\log 2\\ =10.32-0.3\\ =10.02\\ \therefore \mathrm{pH}=10.02\end{array}$