* KCl (Potassium Chloride): This is an ionic compound. Ionic compounds have very strong electrostatic attractions between their ions, leading to high melting and boiling points.
* CO2 (Carbon Dioxide): This is a nonpolar molecule. Nonpolar molecules have weak London dispersion forces, which are the only intermolecular forces present. This results in relatively low boiling points.
* CH2O (Formaldehyde): This is a polar molecule. Polar molecules have dipole-dipole interactions in addition to London dispersion forces. Dipole-dipole interactions are stronger than London dispersion forces, but still weaker than ionic bonds.
Therefore, CO2 (carbon dioxide) will have the lowest boiling point.
Here's why:
* Weakest Intermolecular Forces: CO2 has only weak London dispersion forces between its molecules.
* Smaller Molecular Size: CO2 is a small molecule, which further reduces the strength of these forces.
