Răspuns:
a)
2Na+ Cl2 => 2NaCl
2Mg+O2=> 2MgO
H2O + MgO => Mg(OH)2
SO3+ H2O => H2SO4
H2O + CO2 => H2CO3
b)
MgO
MMgO=24+16=40g/mol
r.at.Mg:O=1:1
r.m.Mg:O=24:16=3:2
H2CO3
MH2CO3=2×1+12+3×16=62g/mol
r.at.H:C:O=2:1:3
r.m.=H:C:O==2:12:48=1:6:24
SO3
MSO3=32+3×16=80g/mol
r.at.S:I=1:3
r.m.S:O=32:48=2:3