(d) $pH = \frac{1}{2}pK_{w} + \frac{1}{2}\log{C + \frac{1}{2}pK_{a}}$ $= \frac{14}{2} + \frac{1}{2}\log{\left( 5 \times 10^{- 3} \right) + \frac{1}{2} \times 4.74}$ $\ = 7 + \frac{1}{2}\lbrack 0.6990 - 3\rbrack + 2.3$ $pH = 8.2195$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.