How much cubic feet does 1 pound of standard air occupy?

The value of 1 pound of standard air occupying 13.33 cubic feet is based on the standard conditions defined for air, which include a temperature of 68°F (20°C) and a pressure of 14.7 psi at sea level. Under these conditions, the density of air can be calculated, leading to the conclusion that one pound of air occupies approximately 13.33 cubic feet. This figure is crucial for various applications in HVAC and sheet metal work, where understanding the properties of air, including its volume and density, is essential for effective design and installation. The other choices do not align with the standard calculations of air density under these conditions.