Mg+2HCl→MgCl2+H2
dd A: MgCl2, HCl dư
khí B: H2
rắn C: Cu, Ag
NaOH+HCl→NaCl+H2O
MgCl2+2NaOH→Mg(OH)2+2NaCl
Mg(OH)2→MgO+H2O
nMgO=4/40=0,1mol
→nMg=0,1mol
→mMg=0,1.24=2,4g
%mMg=2,4/14,2.100%=16,9%
2Cu+O2→2CuO
nCuO=8/80=0,1mol
→mCu=0,1.64=6,4g
%mCu=6,4/14,2.100%=45,07%
%mAg=100-16,9-45,07=38,03%