_9. Rank the following substances in order of increasing average velocity, assuming they are all at the same temperature: O2, CO2, Ar, He A. 02< CO2 < Ar< He B. CO2< Ar <02< He C. Ar< O2< CO2 < He D. CO2< 02 < Ar < He

6. A cylinder of medical oxygen has a volume of 25.4 L, and contains O₂ at a pressure of 125 atm and a temperature of 25 °C. What volume of O₂, does this correspond to at normal body conditions, that is, 1.00 atm and 37 °C? 7. While resting, the average 70-kg human male consumes 14 L of pure O₂ per hour at 25 °C and 100 kPa. How many moles of O₂ are consumed by a 70 kg man while resting for 1.0 hour? 8. What is the molar mass of a gas if 0.281 g of the gas occupies a volume of 125 mL at a temperature 126 °C and a pressure of 777 torr? 9. The density of a certain gaseous fluoride of phosphorus is 3.93 g/L at STP. Calculate the molar mass of this fluoride and determine its molecular formula. 10. A mixture of 2.00 g of H₂, 1.00 g of N₂, and 0.820 g of Ar is stored in a closed container at STP. Find the volume of the container, assuming that the gases exhibit ideal behavior.