In common glass electrode, alkaline error caused at pH > 10 is least for

Concept:

→ In a common glass electrode, the sensitivity of the electrode potential to changes in pH (known as the slope) is influenced by the composition of the electrolyte solution in which it is immersed.

→ One common problem with glass electrodes is the alkaline error, which occurs when the measured potential deviates from the theoretical value at high pH values (above pH 10).

→ To minimize the alkaline error, a high concentration of potassium chloride (KCl) is commonly used as the electrolyte solution. This is because the presence of high concentrations of potassium ions (K⁺) suppresses the ion exchange between the glass membrane and the solution, reducing the effect of the alkaline error.

Explanation:

→ 0.01 M NaCl: This is a relatively low concentration of salt, which may not be sufficient to suppress the alkaline error. In addition, the presence of sodium ions (Na⁺) may not be as effective as potassium ions (K⁺) in reducing the ion exchange between the glass membrane and the solution, leading to a higher alkaline error.

→ 1.0 M NaCl: This is a high concentration of salt, but the presence of sodium ions (Na⁺) may not be as effective as potassium ions (K⁺) in reducing the ion exchange between the glass membrane and the solution, leading to a higher alkaline error.

→ 1.0 M LiCl: Lithium ions (Li⁺) are smaller than potassium or sodium ions, and their smaller size may allow for more effective ion exchange between the glass membrane and the solution, leading to a higher alkaline error.

→1.0 M KCl: A solution of 1.0 M KCl is often used because it is a relatively high concentration that effectively minimizes the alkaline error while still maintaining a reasonable electrical conductivity. Lower concentrations of KCl may not be effective in suppressing the alkaline error, while higher concentrations can lead to increased electrical resistance and polarization effects.

Conclusion:
The correct answer is 1.0 M KCl.