# In Aqueous Solution The Ionization Constants For Carbonic Acid (H2co3) Are K1 = 4.2 × 10−7 And K2 = 4.8 × 10−11. Select The Correct Statement For A Saturated 0.034 M Solution Of The Carbonic Acid. (A) The Concentration Of CO2−3 Is 0.034 M . (B) The Concentration Of H+ Is Double That Of CO2−3 (C) The Concentration Of CO2−3 Is Greater Than That Of HCO−3. (D) The Concentration Of H+ And HCO−3 Are Approximately Equal.

The correct answer is (D). The concentration of H+ and HCO−3 are approximately equal.

$A \rightarrow H_{2}CO_{3} \rightleftharpoons H^{+} + HCO_{3}^{-}$

Here K1 = 4.2 * 10-7

$B \rightarrow HCO_{3}^{-} \rightleftharpoons H^{+} + CO_{3}^{2-}$

Here K2 = 4.8 * 10-11

As K2 < < K1, all major  [H+]total ≈ [H+]A

Where:

[H+]A = H+ ion concentration produce in first step.

From 1 equilibrium, [H+]≈ [HCO3] ≈ [H+]total

[CO3-2] is negligible compared to [HCO3] or [H+]total

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