Answer:
![n_O=6.00molO](https://img.qammunity.org/2021/formulas/chemistry/college/1joub1osj65hdxyklnfegn8lg5ckxdukqe.png)
Step-by-step explanation:
Hello.
In this case, since the molecular formula of barium sulfate is:
![BaSO_4](https://img.qammunity.org/2021/formulas/chemistry/college/rpdqgiri9cp42nh8ap1u8n550a39bqyedl.png)
Which has four oxygen atoms, we can also say that one mole of barium sulfate has four moles of oxygen; in such a way, the moles of oxygen atoms in 1.50 moles of barium sulfate are:
![n_O=1.50molBaSO_4*(4molO)/(1molBaSO_4) \\\\n_O=6.00molO](https://img.qammunity.org/2021/formulas/chemistry/college/cn323c5511d7ont8gath2e1a1498f628r2.png)
Best regards.