VSEPR Theory — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in VSEPR Theory.

Predicting geometry of noble gas compounds and interhalogen compounds

high

Noble gas compounds (like $XeF_2$, $XeF_4$, $XeO_3$) and interhalogen compounds (like $ClF_3$, $BrF_5$, $IF_7$) frequently appear in NEET. These molecules often involve expanded octets and multiple lone pairs, making them excellent test cases for VSEPR theory. Students need to be proficient in calculating steric numbers and correctly placing lone pairs (especially in trigonal bipyramidal electron geometry, where lone pairs prefer equatorial positions) to determine their unique geometries like linear, square planar, T-shaped, or square pyramidal.

Comparison of bond angles in isoelectronic or isostructural species

medium

Questions comparing bond angles are common. A predicted angle is to ask for the order of bond angles in a series of molecules that might be isoelectronic (same number of electrons) or have the same number of atoms but different central atoms or lone pairs (e.g., $NO_2^+$, $NO_2$, $NO_2^-$ or $H_2O$, $H_2S$, $H_2Se$). This tests the nuanced understanding of lone pair repulsion and how it affects bond angles, as well as the influence of electronegativity differences on bond pair repulsion.

Relating VSEPR geometry to molecular polarity and intermolecular forces

high

Understanding molecular geometry is foundational to predicting molecular polarity. NEET often asks questions that require students to first determine the geometry using VSEPR and then deduce if the molecule is polar or nonpolar. This directly impacts understanding intermolecular forces (dipole-dipole, London dispersion, hydrogen bonding) and physical properties like boiling point and solubility. For example, 'Which of the following molecules is nonpolar despite having polar bonds?' is a classic VSEPR-polarity question.