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 hydrogen fluoride, HF, molecule is polar by virtue of polar covalent bonds â in the covalent bond electrons are displaced toward the more electronegative fluorine atom. Ammonia, NH3, molecule the three NâH bonds have only a slight polarity (toward the more electronegative nitrogen atom).