дано
m(CaC2) =1 kg
V практ (C2H2) = 300 L
-----------------------
φ(C2H2)-?
CaC2+2HOH-->Ca(OH)2+C2H2
M(CaC2) = 64 kg/kmol
n(CaC2) = m/M = 1/64 = 0.016 kmol
n(CaC2) = n(C2H2) = 0.016 mol
V теор (C2H2) = n*Vm = 0.016 * 22.4 = 0.3584 m3 = 384.6 L
φ = V( практ C2H2) / V( теорC2H2) * 100% = 300 / 384.6 *100% = 78%
ответ 78%