1)
1. 2Ca + O₂ --> 2CaO
2. CaO + H₂O --> Ca(OH)₂
3. CaO + 2HNO₃ --> H₂O + Ca(NO₃)₂
4. Ca(OH)₂ + 2HNO₃ --> 2H₂O + Ca(NO₃)₂
5. Ca(OH)₂ + 2HCl --> 2H₂O + CaCl₂
2)
1. S + O₂ --> SO₂
2. SO₂ + H₂O --> H₂SO₃
3. SO₂ + Na₂O --> Na₂SO₃
4. Na₂SO₃ + 2HCl --> H₂SO₃ + 2NaCl
5. H₂SO₃ + 2KOH --> K₂SO₃ + 2H₂O
