Which of the following best describes the characteristics of R-22?

R-22, also known as dichlorodifluoromethane, is a commonly used refrigerant in air conditioning systems. This refrigerant is typically characterized as odorless and colorless, which is a critical aspect of its identity. When a refrigerant is odorless and colorless, it indicates that it does not emit any strong or distinct smells, making it less detectable by human senses.

Choosing characteristics such as "foul odor and yellow color" or "colored and smelly" does not accurately reflect R-22's properties, leading to confusion in scenarios involving safety and handling of refrigerants. The option related to being non-toxic may be partially accurate since R-22 is generally considered safe under normal conditions, but the inclusion of a strong odor is misleading, as it would imply the presence of discernible scents, which R-22 lacks.

Recognizing refrigerants like R-22 involves understanding their physical properties, particularly their odor and color, which influence their application and safety in systems. Therefore, the accurate depiction of R-22 aligns with its actual characteristics: being odorless and colorless.