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.
High Frequency (HF) or Radio Frequency (RF) welding is the joining of materials by supplying HF energy in the form of an electromagnetic field (27.12 MHz) and pressure to the material surfaces to be joined. A generator produces the energy. The tool used to supply the energy is called an electrode.