Gas Stoichiometry

The oxidation of phosphine is shown below:

2 PH3(g) + 3 O2(g) → P2O3(s) + 3 H2O(g)

What volume of O2(g), measured at 101 kPa and 50 oC, is consumed in the formation of 20.0 g of P2O3 by this reaction?
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