Ca->Ca(OH)2->CaCl2->Ca(NO3)2->CaSO4
1. Ca + 2H₂O = Ca(OH)₂ + H₂ 2. Ca(OH)₂ + 2HCl = CaCl₂ + 2H₂O 3. CaCl₂ + 2AgNO₃ = Ca(NO₃)₂ + 2AgCl 4. Ca(NO₃)₂ + H₂SO₄ = CaSO₄ + 2HNO₃