1.9 moles
Carbon dioxide (CO₂) is a compound that is made up of carbon and oxygen elements.
It contains 2 moles of oxygen atoms and 1 mole of carbon atoms
Therefore;
We would say, 1 mole of CO₂ → 2 moles of Oxygen atoms + 1 mole of carbon atoms
Thus;
If a sample of CO₂ contains 3.8 moles of oxygen atoms we could use mole ratio to determine the moles of CO₂
Mole ratio of CO₂ to Oxygen is 1 : 2
Therefore;
Moles of CO₂ = 3.8 moles ÷ 2
= 1.9 moles
Hence, the moles of CO₂ present in a sample that would produce 3.8 moles of Oxygen atoms is 1.9 moles