A 2:3 molar ratio mixture of Na2CO3 and MgCO3 produces 0.3 mole of CO2 per mole of the initial mixtureupon strong heating.is it true? If not why?

Na₂CO₃ changes to Na₂O and CO₂ on strong heating where as MgCO₃  changes to MgO and CO₂. 1 mole of CO2 is produced by each being 1 mole initially. The mixture is in the molar ratio 2:3. So, for 1 mole of mixture it will have 0.4 moles of Na₂CO₃ and 0.6 moles of MgCO₃.  So they will produce 1 mole of CO₂. So, your answer is not correct.