S + ? = SO 3 SO 3 + ? = H 2 SO3 H2 SO3+ ? =Na2SO3

Question

S + ? = SO 3
SO 3 + ? = H 2 SO3
H2 SO3+ ? =Na2SO3

Answer 1

1)s+о2
2)so3+н2о
3)h2so3+2naoh