A gas consists of 20.0 mole% CH4, 30.0% C2H6, and 50.0% C2H4. Ten kilograms of this gas is to be compressed to a pressure of 200 bar at 90°C. Using Kay’s rule, estimate the final volume of the gas.

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?