Activation Energy — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Activation Energy.

Arrhenius Equation with Graphical Interpretation

high

NEET often tests the graphical representation of the Arrhenius equation ($ln k$ vs $1/T$). Students might be asked to determine $E_a$ from the slope of such a plot, or to identify the correct plot for a given reaction. This combines numerical ability with graphical analysis, making it a comprehensive test of understanding. Questions might involve comparing two reactions based on their Arrhenius plots.

Combined Effect of Catalyst and Temperature

medium

A question could involve a scenario where both temperature is changed and a catalyst is added. Students would need to apply the Arrhenius equation twice or understand the multiplicative effect on the rate constant. For example, calculating the factor by which a reaction speeds up when both $T$ increases and $E_a$ decreases due to a catalyst. This tests a deeper understanding of the interplay of factors affecting reaction rate.

Activation Energy in Multi-step Reactions

low

While less common for NEET, a question could touch upon activation energy in multi-step reactions, where the overall rate is determined by the slowest step (rate-determining step), which corresponds to the highest activation energy barrier in the reaction mechanism. This would require interpreting a more complex energy profile diagram with multiple transition states and intermediates. It tests an advanced conceptual understanding of reaction mechanisms.

Relationship between $E_a$, $E_{a, ext{reverse}}$ and $Delta H$

high

This is a fundamental relationship: $Delta H = E_{a, ext{forward}} - E_{a, ext{reverse}}$. Questions frequently provide two of these values and ask for the third, often in conjunction with an energy profile diagram. This tests the ability to apply basic energy conservation principles within reaction kinetics and interpret graphical data correctly.