Which of the following is a common refrigerant?

The selection of "All of the above" as a common refrigerant is accurate because Freon, ammonia, and carbon dioxide are all widely utilized in various refrigeration and air conditioning systems.

Freon is a brand name for a group of chlorofluorocarbons (CFCs) that were historically the most commonly used refrigerants in household and commercial applications due to their efficiency and relatively low toxicity. However, due to environmental concerns regarding ozone depletion, the use of CFCs has decreased significantly, leading to the adoption of other refrigerants.

Ammonia is another common refrigerant, primarily used in industrial refrigeration systems. It has excellent thermodynamic properties and is highly efficient, although it is toxic and requires careful handling.

Carbon dioxide is also gaining popularity as a refrigerant, especially in systems designed for lower environmental impact. It is non-toxic, non-flammable, and has low global warming potential, making it a suitable option for modern refrigeration needs.

Each of these substances has unique properties that make them suitable for specific applications in the refrigeration industry, contributing to their classification as common refrigerants.