One ecologically important equilibrium is that between carbonate and hydrogen carbonate ions in natural water. This standard Gibb's energies of formation of `CO_(3)^(-2)(aq)` and `HCO_(3)^(Theta)(aq)` are `-527.8 kJ mol^(-1)` and `-586.8 kJ mol^(-1)` respectively.
For water,
`2H_(2)O(l) +2e^(Theta) rarr H_(2)(g) +2OH^(Theta)(aq) , E_(RP)^(Theta) =- 0.83 V`
`2H_(2)O rarr O_(2) +4H^(+) +4e^(Theta), E_(OX)^(Theta) = - 1.23V`
The value of `pK_(a)` for `HCO_(3)^(Theta)` (aq) is (approx):

Options

A. `9.3`
B. `10.3`
C. `8.3`
D. `11.3`

Answer

B