In one gram of carbonate (M2O3) on treatment with excess HCL produces 0.01186 moles of carbon dioxide. The molecular mass of M2O3 in g mol- is?

From the balanced chemical equation: M2O3 + 6HCl -> 2MCl3 + 3H2O + CO2. Since 1 mole of carbonate produces 1 mole of CO2, the molecular mass of M2O3 is 6 × 35.5 g mol–1 as 6HCl is needed to produce 1 mole of CO2, giving a total molecular mass of 213 g mol–1.