[AWK]

K=a_H3O⁺ · a_CO3^2- / a_HCO3^-
a_H3O⁺ = K · a_HCO3^- / a_CO3^2-
pH = pK_a + log(a_CO3^2-/a_HCO3^-)

a= γ · c

[BHAVESH]

pH will be 9.844

Ok the mistake was I was doing that
1) I was not considering given concentration of HCO₃^- & CO₃^-2
2) In back of my mind, I was considering H₃O⁺ ion concentration also as 0.01 M
3) I was not considering Equation of K = [CO₃^-2][H₃O⁺]/[HCO₃^-] in which Standard K is already given as 4.8 X 10^-11
4) I was not considering concentrations of all ions with correction of γ Value.
5) I did not have in my mind to use Handerson equation there after.

Thank you very much AWK for teaching me.
IF any of my mistake is left apart from above mentioned, please do let me know.

Wonderful teaching..