Surface Chemistry — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Surface Chemistry.

Distinction between Adsorption Types with Application

high

The fundamental difference between physisorption and chemisorption, including their characteristics (forces, reversibility, layers, enthalpy, temperature effect), is a perennial favorite. A question might present a scenario (e.g., a catalyst working at high temperature) and ask which type of adsorption is involved, or ask for an incorrect statement about one type. This tests both recall and application of concepts. For example, 'Which type of adsorption is responsible for the working of a gas mask and why?'

Properties and Classification of Colloids

high

Questions on colloids are almost guaranteed. This includes identifying types of colloids (lyophilic/lyophobic, multimolecular/macromolecular/associated), their preparation, purification methods (dialysis, ultrafiltration), and especially their unique properties like Tyndall effect, Brownian movement, electrophoresis, and coagulation (Hardy-Schulze rule). A question might involve a diagram of Tyndall effect or ask to arrange ions by coagulating power. For example, 'A beam of light is passed through three different solutions. Only one shows a visible path. Identify the type of solution and explain the phenomenon.'

Catalysis: Characteristics and Mechanism

medium

While less frequent than adsorption/colloids, catalysis is important. Questions often focus on the general characteristics of catalysts (specificity, activity, selectivity), their effect on activation energy and equilibrium, and the role of promoters/poisons. The mechanism of heterogeneous catalysis (adsorption theory) is also a potential area. For example, 'Which of the following statements is incorrect regarding the action of a catalyst?' or 'Explain why finely divided iron is used as a catalyst in the Haber process.'

Micelles and Emulsions: Formation and Types

medium

The concept of Critical Micelle Concentration (CMC), the structure of micelles, and the classification of emulsions (O/W vs. W/O) with examples and emulsifying agents are recurring themes. Questions might test the conditions for micelle formation or ask to identify the type of emulsion from a given example. For example, 'What happens to surfactant molecules below and above their Critical Micelle Concentration?' or 'Identify the type of emulsion in butter and name a common emulsifying agent.'