nHCl = 0.25*1=0.25 (mol)
Mg + 2HCl => MgCl2 + H2
.........0.25.......................0.125
VH2 = 0.125*22.4=2.8(l)
\(n_{HCl}=0,25.1=0,25\left(mol\right)\)
PTHH: Mg + 2HCl → MgCl2 + H2
Mol: 0,25 0,125
\(\Rightarrow V_{H_2}=0,125.22,4=2,8\left(l\right)\)