Development of the Modern Freezer. Bacteria are usually the cause of food decay, but they can't grow as well or at all in freezing temperatures, which are at 32 degrees Fahrenheit (0 degrees Celsius) or lower.
HF- polar molecule: dipole-dipole forces. There are also dispersion forces and H bond between HF. BF3- nonpolar: dispersion forces. Ar- Dispersion forces between Ar atoms.
The abnormality of HF is due to the presence of hydrogen bonding. They are covalent substances soluble in polar solvents. The bond strength of HX decreases down the group as the bonds become less polar. This property governs the reactivity of the halides.