Solubility Product Constant — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Solubility Product Constant.

Combined Effect of pH and Common Ion

medium

NEET has started to introduce questions that combine multiple concepts. A problem could involve calculating the solubility of a metal hydroxide (e.g., $Fe(OH)_3$) in a solution that is not only buffered at a certain pH but also contains a common metal ion from another source. This would require students to first determine the $[OH^-]$ from pH, then consider the common ion effect for the metal cation, and finally use the $K_{sp}$ expression. This tests a deeper understanding of ionic equilibria and approximation techniques.

Selective Precipitation with Multiple Ions

high

Questions asking to separate a mixture of ions by selective precipitation are common in competitive exams. A NEET question could present a solution containing two different metal ions (e.g., $Ba^{2+}$ and $Sr^{2+}$) and ask which ion will precipitate first upon gradual addition of a common precipitating agent (e.g., $SO_4^{2-}$). This requires comparing the $K_{sp}$ values and calculating the concentration of the precipitating ion needed for each metal ion to start precipitating, or determining the concentration range for selective precipitation. This tests both conceptual understanding and calculation skills.

Solubility in Presence of Complexing Agents

low

While the effect of complex ion formation on solubility is part of the detailed explanation, direct quantitative problems involving stability constants ($K_f$) are less common in NEET for $K_{sp}$ context, often being considered a more advanced topic. However, a qualitative or semi-quantitative question might appear, asking to identify conditions that *increase* solubility beyond just pH or common ion effects, with complexation being an option. For example, 'Why does AgCl dissolve in ammonia solution?' This would test the conceptual understanding without complex calculations. A full calculation problem would be 'hard' but not impossible.