14. How doesthe density ofa gasdepend on temperature?Pressure? How doesit depend on the molar massof the gas? 15. What is partial pressure?

14. How doesthe density ofa gasdepend on temperature?Pressure? How doesit depend on the molar massof the gas? 15. What is partial pressure?What is the relationship between the partial pressuresof each gas in a sample and the total pressure of gas in the sample? 16.Why do deep-sea divers breathe mixtureof heliumand orygen? A 17. When a gas is collectedover water, is the gas pure?Why or why not? How can the partial pressureof the desiredgas be determined?