Let f and g be two functions given by f = {(2, 4), (5, 6), (8, -1), (10, -3)} and g = {(2, 5), (7, 1), (8, 4), (10, 13), (11, -5)} Find the domain of f + g.
Valency of iron in FeCl2 and FeCl3 is _______ and _______ respectively.