Pair of Molecules Having Non-Linear Structures: ICl₂⁻, BeH₂, CS₂, I₃⁻, SCl₂, ClO₂⁻, XeF₂, CN₂²⁻ VSEPR Analysis

The correct answer is (C) SCl₂ and ClO₂⁻.

Both SCl₂ and ClO₂⁻ have bent (non-linear) molecular geometries due to lone pairs on their central atoms repelling bond pairs under VSEPR theory.

Option Analysis

(A) ICl₂⁻ and BeH₂

ICl₂⁻ features iodine as the central atom with 22 valence electrons, forming AX₂E₃ (trigonal bipyramidal electron geometry, linear molecular shape from two axial bonds and three equatorial lone pairs). BeH₂ has beryllium with two bonding pairs and no lone pairs (AX₂), yielding a linear structure. Both are linear.

(B) CS₂ and I₃⁻

CS₂ (S=C=S) has 16 valence electrons around central carbon (AX₂), resulting in linear geometry. I₃⁻ is AX₂E₃ like ICl₂⁻, with linear molecular shape (trigonal bipyramidal electron geometry). Both linear.

(C) SCl₂ and ClO₂⁻

SCl₂ has sulfur central (AX₂E₂, tetrahedral electron geometry, bent molecular shape from two lone pairs compressing the Cl-S-Cl angle below 109.5°). ClO₂⁻ (chlorite ion) is also AX₂E₂ (20 valence electrons, bent or V-shaped). Both non-linear.

(D) XeF₂ and CN₂²⁻

XeF₂ is AX₂E₃ (linear molecular geometry). CN₂²⁻ (carbodiimide form [N=C=N]²⁻) has central C as AX₂ (linear). Both linear.

The pair of molecules having non-linear structures is a key VSEPR theory question for CSIR NET Life Sciences and chemistry exams, testing molecular geometry knowledge.

VSEPR Theory Basics

Valence Shell Electron Pair Repulsion (VSEPR) predicts shapes by minimizing lone pair-bond pair repulsions. AXₙEₘ notation defines geometry: AX₂E₂ yields bent (non-linear) shapes like water.

Linear Molecules Breakdown

• ICl₂⁻, I₃⁻, XeF₂: AX₂E₃ (trigonal bipyramidal electrons, linear shape)
• BeH₂, CS₂, CN₂²⁻: AX₂ (no lone pairs, 180° bond angle)

Non-Linear Pair: SCl₂ and ClO₂⁻

• SCl₂: Sulfur (6 valence e⁻ + 2Cl + 4 lone pair e⁻) = AX₂E₂, bent (~103° angle)
• ClO₂⁻: Chlorine (7 + 12 + 1 charge + 4 lone) = AX₂E₂, bent (<109.5°)

Molecular Geometry Summary Table