Na + H2O -> NaOH + 1/2 H2
x x
Ca + 2H2O -> Ca(OH)2 + H2
y y
Ca(OH)2 + H2SO4 -> CaSO4 + 2H2O
y y y
2NaOH + H2SO4 -> Na2SO4 + 2H2O
x x/2 x/2
Gọi nNa = x mol; nCa = y mol
nH2SO4 = 0,4 mol
Có: $\left \{ {{0,5x+y=0,4} \atop {23x+40y=8,3}} \right.$
=> Nghiệm âm => Sai đề