Number of moles of acetylene in 52 g of acetylene gas? Number moles of water produced for each mole of acetylene used?

Molar mass of C₂H₂ (acetylene) = (12×2 + 1×2) g/mol = 26 g/mol
Number of C₂H₂ = (52 g) / (26 g/mol) = 2 mol

2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
Mole ratio C₂H₂ : H₂O = 2 : 2 = 1 : 1
Number of moles of H₂O produced = (2 mol) × (1/1) = 2 mol