Final answer:
Liquid nitrogen is made by the liquefaction of atmospheric air and is commonly used as a refrigerant. Flash-freezing biological materials in a bath of liquid nitrogen helps preserve them without degradation.
Step-by-step explanation:
Liquid nitrogen is made by the liquefaction of atmospheric air through compression and cooling. It is commonly used as a refrigerant and has various applications in biology, medicine, and technology. When biological materials, such as blood or sperm, are flash-frozen in a bath of liquid nitrogen, it allows for their long-term preservation without degradation.