At what temperature does the density of vapor remain constant at 0.0252 ft3/lb.?

The density of a vapor depends on both temperature and pressure. For many gases, including refrigerants and air, as the temperature increases, the density typically decreases if the pressure remains constant. When the question indicates a constant density of 0.0252 ft³/lb, it implies a specific state or condition where the temperature has stabilized to maintain that density under the prevailing pressure conditions.

The correct choice signifies the temperature at which the properties of the vapor, particularly its density, remain unchanged despite variations in other environmental factors, as long as the pressure is sustained. Hence, the answer points to a specific temperature threshold that correlates with the defined density of 0.0252 ft³/lb for that particular vapor, confirming that at 36 degrees, the density remains stable at the stated value. This reflects a fundamental principle of thermodynamics in gas behavior.