The Valence Shell Electron Pair Repulsion Vsepr Theory

To determine the non-linear molecule-pair, let's analyze the molecular geometries of each compound using VSEPR (Valence Shell Electron Pair Repulsion) theory:

1. XeF₂: Xenon difluoride has a linear geometry. The central xenon atom has 2 bonding pairs and 3 lone pairs of electrons, leading to a linear structure.

2. NO₂: Nitrogen dioxide has a bent or V-shaped geometry. The nitrogen atom has 2 bonding pairs and 1 lone pair, resulting in a non-linear shape.

3. HCN: Hydrogen cyanide is a linear molecule. The carbon is triple-bonded to nitrogen and single-bonded to hydrogen, leading to a straight-line structure.

4. ClO₂: Chlorine dioxide has a bent geometry due to 2 bonding pairs and 1 lone pair on the central chlorine atom.

5. CO₂: Carbon dioxide has a linear geometry. The carbon atom is double bonded to two oxygen atoms, forming a straight line.

Now, let's identify the non-linear pairs:
- XeF₂ is linear.
- CO₂ is linear.
-HCN is linear.
-NO₂ is non-linear (bent).
- ClO₂ is non-linear (bent).

Answer: ClO₂, NO₂