Which of the following reactions are combination reactions? Reaction 1: 2 KClO3 ---> 2 KCl + 3 O2 Reaction 2: MgO + H2O ---> Mg(OH)2 Reaction 3: 4 Al + 3 O2 ---> 2 Al2O3 Reaction 4: Zn + FeSO4 ---> ZnSO4 + Fe Which of the following reactions are combination reactions? Reaction 1: 2 KClO3 ---> 2 KCl + 3 O2 Reaction 2: MgO + H2O ---> Mg(OH)2 Reaction 3: 4 Al + 3 O2 ---> 2 Al2O3 Reaction 4: Zn + FeSO4 ---> ZnSO4 + Fe Reaction 1 Reaction 2 Reaction 3 Reaction 4 None of the above