0.72gm of an oxide of a metal M on reduction with H2 gave 0.64g of the metal. The atomic weight of the metal is 64. The empirical formula of the compound is

Weight of metal oxide = 0.72gWeight of metal = 0.64gWeight of Oxygen = 0.08gEM = 64Atomic weight  of metal = 64Equivalent weight  of metal = 64 Valency of metal = 1Valency of Oxygen = 2Criss-Cross methodFormula of the metal oxide is M2O