classify each of the following chemical equations as a (i) combination reactions, (ii) decomposition reaction, (iii) displacement reaction, or (iiii)partner-exchange reaction. (a) Fe 3 O 4 + 4H 2 (g) → 3Fe(s) + 4H 2 O (b) 2KClO 3 (s) → 2KCl(s) + 3O 2 (g) (c) H 2 O + C → H 2 + CO (d) Cl 2 O 7 (g) + 2H 2 O(l) →2 HClO 4 (aq) (e) Ca 3 (PO 4 ) 2 (s) + 3H 2 SO 4 (aq) → 3CaSO 4 (s) + 2H 3 PO 4 (aq) (f) Potassium reacts with water to give aqueous potassium hydroxide and gaseous hydrogen. 2K + 2H 2 O →2KOH + H 2 ↑ (g) Solid magnesium carbonate decomposes to form solid magnesium oxide and gaseous carbon dioxide. MgCO 3 →MgO + CO 2