Which of these is a reason why CFCs were originally favored as refrigerants?

CFCs (chlorofluorocarbons) were favored as refrigerants primarily due to their suitable volatility and non-toxicity. These properties made them ideal for use in refrigeration and air conditioning systems. CFCs have a low boiling point, which allows them to easily evaporate and absorb heat during the refrigeration cycle, making them effective in cooling applications. Additionally, they are non-toxic to humans and have a relatively low risk of causing harm if leaks occur, enhancing their appeal for household and commercial use.

The other reasons do not align with the characteristics that made CFCs popular as refrigerants. For example, CFCs are not highly reactive; in fact, their stability (not reactivity) contributed to issues such as ozone depletion in the atmosphere. Additionally, while CFCs are man-made and not produced from natural resources, the ease of production is not the primary reason for their use as refrigerants. Lastly, although cost can be a factor in choosing refrigerants, CFCs were primarily favored for their effective cooling properties and safety profile rather than being the cheapest option available.