Packing Efficiency — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Packing Efficiency.

Combined Density and Packing Efficiency Calculation

high

NEET often combines concepts. A question might provide the density and atomic mass of an element crystallizing in a specific lattice (e.g., FCC) and ask for its atomic radius. This requires using the density formula, knowing 'Z' for FCC, and then using the 'a-r' relationship for FCC to find 'r'. This tests multiple related concepts in one problem, making it a good differentiator.

Comparison of Void Space and Coordination Number

medium

Instead of directly asking for packing efficiency, questions might ask to compare the percentage of void space or relate packing efficiency to coordination number. For instance, 'Which structure has the highest coordination number and lowest void space?' This requires understanding the inverse relationship between packing efficiency and void space, and the direct relationship with coordination number for different structures.

Packing Efficiency in Ionic Solids (beyond simple spheres)

low

While the core NEET syllabus focuses on identical spheres, a slightly advanced question could involve a simple ionic solid (like NaCl type) where cations occupy voids in an anion lattice. This would require understanding how the radii of two different ions affect the overall packing and void filling, moving beyond the identical sphere model. This is less common but could be a 'hard' question.