Answer
$2.4\times 10^{22} molecules$
Work Step by Step
We can determine the required number of oxygen molecules as follows:
$N=\frac{pVN_A}{RT}$
We plug in the known values to obtain:
$N=\frac{(101300)(0.001)(6.02\times 10^{23})}{8.31(310)}$
This simplifies to:
$N=2.4\times 10^{22} molecules$