What volume of ethyne at STP is produced when 6.4 g of calcium carbide reacts with excess water (Ca = 40, C = 12, molar volume = 22.4 dm³)?

Correct answer C. 2.24 dm³

Explanation

CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂. Moles of CaC₂ = 6.4/64 = 0.10 mol, giving 0.10 mol ethyne. Volume = 0.10 × 22.4 = 2.24 dm³.