AIIMS 2018 Chemistry Acid-Base Equilibria MCQ Question

The calculation provided indicates that the dissociation constant $K_a$ for the acid is derived from the formula $K_a = \frac{[H^+]^2}{C}$, where $[H^+]$ is the concentration of hydrogen ions and $C$ is the initial concentration of the acid. Substituting the given values, $K_a = \frac{(3.6 \times 10^{-4})^2}{0.02} = 6.48 \times 10^{-6}$, confirms that the calculated $K_a$ aligns with the expected dissociation behavior of weak acids. Since the other options are not applicable or do not provide relevant information, they are not considered correct in this context.