Final answer:
The closest approximate mass of 400 SCF of LPG would be 5.5 kg, based on common density values for LPG and the given information about energy content per gallon of liquid propane.
Step-by-step explanation:
The question pertains to converting a quantity of liquid propane gas (LPG) measured in standard cubic feet (SCF) to kilograms. To find the approximate mass of 400 SCF of LPG, we can use the information provided in the Therm explanation, which says that one gallon of LPG contains 91,500 British thermal units (Btu) and is equivalent to 0.915 Therms. Given the density of liquid propane (density 0.5005 g/L), we can first convert the volume from SCF to gallons or liters, then to kilograms using the density value.
Using the fact that there are approximately 91,500 Btu in one gallon of LPG, and knowing that 400 SCF is close to 3 gallons, we can estimate the weight. However, we don't have a precise density figure for LPG versus liquid propane to make an exact conversion. Based on common values for LPG density (which can vary slightly depending on composition, around 0.495 to 0.565 kilograms per liter), 400 SCF would fall between 4.5 kg and 5.5 kg. Therefore, the closest approximate answer is option 2) 5.5 kg.