Air is a mixture of several gases. The 10 most abundant of these gases are listed here along with their mole fractions and molar masses.

Component	Mole fraction	Molar mass (g mol1g mol1)
Nitrogen	0.780 84	28.013
Oxygen	0.209 48	31.998
Argon	0.009 34	39.948
Carbon dioxide	0.000 375	44.0099
Neon	0.000 018 18	20.183
Helium	0.000 005 24	4.003
Methane	0.000 002	16.043
Krypton	0.000 001 14	83.80
Hydrogen	0.000 000 5	2.0159
Nitrous oxide	0.000 000 5	44.0128

Part A What mass of carbon dioxide is present in 1.00 m3 of dry air at a temperature of 25 C and a pressure of 687 Torr ? Express your answer with the appropriate units.

Part B Calculate the mass percentage of oxygen in dry air. Express your answer with the appropriate units.