If 400 g of water are produced from combustion of ethane, how many grams of thane reacted? and how to calculate.?

Molar mass of H₂O (water) = (1.0×2 + 16.0) g/mol = 18.0 g/mol
Molar mass of C₂H₆ (ethane) = (12.0×2 + 1.0×6) g/mol = 30.0 g/mol

Equation of the reaction :
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
OR: Mole ratio C₂H₆ : H₂O = 2 : 6 = 1 : 3

No. of moles of H₂O produced = (400 g) / (18.0 g/mol) = 22.2 mol
No. of moles of C₂H₆ reacted = (22.2 mol) × (1/3) = 7.41 mol
Mass of C₂H₆ reacted = (7.41 mol) × (30.0 g/mol) = 222 g