Final answer:
The refrigerant pressure of an R-12 system at room temperature varies depending on the specific factors and conditions of the system.
Step-by-step explanation:
The refrigerant pressure of an R-12 system when idle at room temperature (72°F) depends on several factors, including the specific properties of R-12 and the conditions of the system. As an example, at a temperature of 72°F, R-12 is typically in the form of a gas. The pressure of the refrigerant at this temperature would vary based on the specific application and system design.
However, it's important to note that R-12 (also known as dichlorodifluoromethane) is no longer widely used, as it has been phased out due to its harmful effects on the ozone layer. Currently, the common refrigerant used is R-134a.