B:SO2
C:H2O
D:SO3
E:H2SO3
F:H2SO4
G:BaSO4
X:HCl
(1)E的化学是为:H2SO3
(2)S+O2=点燃=SO2
(3)SO3+H2O=H2SO4
(4)H2SO4+BaCl2=BaSO4↓+2HCl