Which refrigerants are commonly used in refrigeration systems?

The correct answer identifies a set of refrigerants that are widely recognized and utilized in various refrigeration systems. R-22, R-410A, R-134a, and ammonia are all refrigerants that have been frequently used in commercial and residential applications.

R-22, known as HCFC-22, has been a primary refrigerant for air conditioning systems for many years, although its use is being phased out due to environmental concerns. R-410A is a newer blend that does not contain chlorine and is more environmentally friendly, making it a popular choice for modern refrigerant systems. R-134a is extensively used in automotive air conditioning and refrigeration systems because of its relatively low environmental impact compared to older refrigerants. Ammonia, while primarily used in industrial applications, is recognized for its efficiency as a refrigerant and has a long history of use.

The other options include refrigerants that might not be as commonly associated with refrigeration systems. R-12 and R-123, for example, have been phased out due to their ozone-depleting properties. While R-404A and CO2 are used, they are not as prevalent for residential air conditioning. Some options mix refrigerants with different applications, which can be misleading. Thus