дано
m(Ca) = 20 g
V(H2)-?
Ca+H2SO4-->CaSO4+H2
M(Ca) = 40 g/mol
n(Ca) =m/M = 20/40 = 0.5 mol
n(Ca) = n(H2) = 0.5 mol
V(H2) = n*Vm = 0.5*22.4 = 11.2 L
ответ 11.2 л
