Answer:
3.01 * 10^23 oxygen atoms
Step-by-step explanation:
Water is H2O. So there are one oxygen atom for every molecule of water.
So in 5.0 mol of water molecules, there are 5.0 mol of oxygen atoms.
Since 5.0 mol = 5 * 6.02 * 10^23 molecules, there are 3.01 * 10^23 oxygen atoms.