If 10.0 ml of 0.500 mol/L sodium hydroxide solution, NaOH(aq), is added to 30.0 ml of 0.340 mol/L hydrocyanic acid, HCN(aq), what is the pH of the solution? (Given that Kₐ for HCN(aq) is 9.31)
a. 2.15
b. 4.18
c. 7.00
d. 9.31