Which statement best aligns with the Dewar flask's use in the material?

• A. To store compressed gases
• B. To insulate and store cryogenic liquids
• C. To measure gas pressure
• D. To heat liquids rapidly

Answer: (B)

The Dewar flask is built to keep very cold liquids from warming up and boiling away. It achieves that by having a double wall with a vacuum in between, which greatly reduces heat transfer by conduction, convection, and radiation. The narrow neck and sometimes a stopper help limit any remaining heat in from the surroundings, so the liquid stays at cryogenic temperatures longer. This design makes it ideal for insulating and storing cryogenic liquids such as liquid nitrogen or other extremely cold fluids. It wouldn’t be used to store compressed gases in a pressurized way, to measure gas pressure, or to heat liquids rapidly, since those aren’t functions of an insulated cryogenic storage vessel.