(i) Iron react with steam to form the metal oxide and hydrogen.
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g)
(ii) The reaction of calcium with water is exothermic but the heat evolved is not sufficient for the hydrogen to catch fire.
Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)