The minimum amount of O2(g) consumed per gram of reactant is for the reaction : (Given atomic mass : Fe = 56, O = 16, Mg = 24, P = 31, C = 12, H = 1)
(1) 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)
(2) P4(s) + 5 O2(g) → P4O10(s)
(3) C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l)
(4) 2Mg(s) + O2(g) →MgO(s)
