Balance chemical equation for said reation is as follow,
CO₂ + 2 H₂O → CH₄ + 2 O₂
According to this equation,
1 Molecule ( 1 mole) of CO₂ reacts with 2 Molecules ( 2 moles) of H₂O to produce 1 Molecule ( 1 mole) of CH₄ and 2 Molecules ( 2 moles) of O₂.
So, if we take 5 molecules of CO₂ and 10 molecules of CH₄, it means we have multiplied the equation with 5. So, the equation will be,
5 CO₂ + 10 H₂O → 5 CH₄ + 10 O₂
As there are 10 molecules of O₂ formed and each oxygen molecule contains 2 oxygen atoms, so the number of atoms in 190 molecules will be,
= 10 × 2
= 20 Atoms of Oxygen
