Answer:
4g
Step-by-step explanation:
Equation of reaction
2H₂ + O₂ → 2H₂O
Molar mass of O2 = 16g/mol
Molar mass of water = 18g/mol
Number of moles = mass / molar mass
Mass = molar mass × number of moles
Mass of O2 = 1 × 16 = 16g
Mass of H2O = 2 × 18 = 36g
So from equation of reaction,
16g of O2 = 36g of H2O
X of O2 = 9g of H2O
X = (9 × 16) / 36
X = 4g
4g of O2 will produce 9g of H2O