Answer
9.43 g O
Work Step by Step
Use the density of air to convert grams of air into liters of air. Use the percent by volume of oxygen as a conversion factor in order to convert liters of air into liters of oxygen. Then use the molar volume of a gas at STP as a conversion factor to convert liters of oxygen into moles of oxygen. Finally, use molar mass of oxygen to determine the grams of oxygen.