Which statement correctly characterizes natural refrigerants?

Which statement correctly characterizes natural refrigerants?

• A. They are all non-flammable
• B. They are all synthetic
• C. They include CO2 and ammonia
• D. They are never used in industrial systems

Answer: (C)

Natural refrigerants are substances found in nature that are used for cooling and typically have very low global warming potential and no ozone depletion potential. Carbon dioxide and ammonia are classic examples, so saying that natural refrigerants include CO2 and ammonia is correct. These refrigerants differ in safety and handling: CO2 is non-flammable and non-toxic at common concentrations, while ammonia is toxic and requires careful containment, and other natural options like hydrocarbons are flammable. They are indeed used in industrial systems, so the idea that natural refrigerants are never used is false. In summary, CO2 and ammonia are representative natural refrigerants, which is why this statement best characterizes them.

Natural refrigerants are substances found in nature that are used for cooling and typically have very low global warming potential and no ozone depletion potential. Carbon dioxide and ammonia are classic examples, so saying that natural refrigerants include CO2 and ammonia is correct. These refrigerants differ in safety and handling: CO2 is non-flammable and non-toxic at common concentrations, while ammonia is toxic and requires careful containment, and other natural options like hydrocarbons are flammable. They are indeed used in industrial systems, so the idea that natural refrigerants are never used is false. In summary, CO2 and ammonia are representative natural refrigerants, which is why this statement best characterizes them.