Common Ion Effect — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Common Ion Effect.

Solubility of a complex salt in presence of common ion, with pH consideration.

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NEET often combines multiple concepts. A question might involve a salt like $Zn(OH)_2$ where $K_{sp}$ is given, and ask for its solubility in a buffer solution of a specific pH. This tests the calculation of $[OH^-]$ from pH, applying the common ion effect, and handling the stoichiometry of $Zn(OH)_2$. It's a comprehensive test of related equilibrium concepts.

Comparison of relative solubilities of two different salts in the presence of the same common ion.

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Instead of asking which precipitates first, a question could provide two sparingly soluble salts (e.g., $AgCl$ and $AgBr$) and their $K_{sp}$ values, then ask to compare their solubilities in a solution containing a fixed concentration of a common ion (e.g., $Ag^+$ from $AgNO_3$). This tests the ability to apply the common ion effect to multiple equilibria and compare the resulting solubilities.

Impact of common ion on the degree of dissociation of a weak acid/base (buffer-related).

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While the common ion effect is primarily discussed for solubility, it's also fundamental to weak acid/base equilibria and buffer solutions. A question might ask how the addition of a salt of the conjugate base affects the dissociation of a weak acid, or vice-versa. This would be a conceptual question testing the broader application of Le Chatelier's principle related to common ions, but in an acid-base context rather than solubility.