A weak acid HA after treating with 12 mL of 0.1 M strong base BOH has a pH of 5. At the end point the volume of same base required is 26.6 mL. Calculate the Kₐ of an acid.
A. 1.8×10⁻⁵
B. 8.22×10⁻⁶
C. 1.8×10⁻⁶
D. 8.2×10⁻⁵