Reactions

1. Action of water on quick lime:

   CaO + H₂O → Ca(OH)₂

2. Action of heat on ferrous sulphate crystals:

   2FeSO₄ → Fe₂O₃ + SO₂ + SO₃

3. Iron nails kept in copper sulphate solution:

   Fe + CuSO₄ → FeSO₄ + Cu

4. Reaction between sodium sulphate and barium chloride solutions:

   Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl