JEE Main 2023 — Electrochemistry Question with Solution

In volumetric analysis, the concentration of a solution is a crucial factor in determining the accuracy of the results. In the case of an aqueous solution of KOH, the concentration can change over time due to the absorption of atmospheric CO₂. This occurs because KOH is a basic (alkaline) solution and reacts with carbon dioxide (CO₂) from the air to form potassium carbonate (K₂CO₃).

The reaction between KOH and CO₂ is given by :

KOH + CO₂ $$\to$$ K₂CO₃

This reaction will change the concentration of KOH in the solution, which in turn will impact the accuracy of the results obtained in volumetric analysis. For example, if the concentration of KOH is lower than it was when the solution was prepared, then more solution will be needed to reach the endpoint in a reaction, and the results will be inaccurate.

That's why it is important to check the concentration of the KOH solution before using it for volumetric analysis, as stated in the assertion (A). And the reason (R) provides the explanation for why the concentration should be checked. Hence, both the assertion and the reason are correct and the correct answer is (D). Both (A) and (R) are correct and (R) is the correct explanation of (A).