How many grams of water have the same number of oxygen atoms as 1.0 mol of oxygen gas?

As we know 1 mole of O₂ gas contain 6.022 × 10²³ Molecules.
And,
1 mole of O₂ contains 6.022 × 10²³ × 2 Oxygen atoms.

Also,
1 mole of H₂O contains 6.022 × 10²³ Oxygen atoms.
So,
2 moles of H₂O will have 6.022 × 10²³ × 2 Oxygen atoms.

Therefore, we need to take 2 moles of water as 2 moles of water contains exactly the same number of oxygen atoms as that 1 mole of O₂ gas contains.
So,

                                      1 Mole of H₂O  =  18 g
Then,
                                    2 Moles of H₂O  =  X g

Solving for X,
                                  X  =  (2 mol × 18 g) ÷ 1 mol

                                  X  =  36 g H₂O
Result:
            36 g of H₂O have the same number of Oxygen Atoms as contained by 1 Mole of O₂ gas.

You would do 1500/4 and the answer is 375