In an experiment, 4 g of M2Ox oxide was reduced to 2.8 g of the metal. If the atomic mass of the metal is 56 g mol-1, the number of O-atoms in the oxide is

Mass of oxygen in oxide = 4- 2.8 = 1.2 g Equivalent weight of metal = Mass of metal  Mass of oxygen ×8                                        =2.81.2×8=18.67 Valency of metal = Atomic weight of metal  Eq. weight of metal =5618.67=3