Which of the following relationships establishes the condition for two weak monoprotic acid solution — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

Isohydric solutions have the same hydronium ion concentration, $[H^+]$. For weak acids (where $\alpha \ll 1$), $[H^+] \approx \sqrt{K_a C}$. Equating the two yields $\sqrt{K_{a1}C_1} = \sqrt{K_{a2}C_2}$, which squares to $K_{a1}C_1 = K_{a2}C_2$.