Under the same conditions of pressure and temperature, 9.56 mL of a mixture of CO and CO2 effuse through the hole in the same amount of time. In 2.00 min, 28.7 mL of He effuse through a small hole. Determine the percent composition by volume of the mixture. The effusion rate of a gas is proportional to its root-mean-square speed, explain which is related to its molar mass.