A 2.684-g sample of zinc oxide was reduced by hydrogen gas, resulting in 2.156 g of pure zinc metal. Determine the empirical formula of the initial zinc oxide.

Reacting masses1 calcium carbonate breaks down on heating to produce calcium oxide and carbondioxide gas.caco3 + cao + co2a student heats 15 g of calcium carbonate strongly in a crucible.relative atomic masses (a): ca = 40, c = 12, o = 16.calculate the mass of calcium oxide produced by this reaction.(5 marks)