1. Calculate the molecular mass of CaCO₃ at mass Ca=40u,C=12u,O=16u
2. Verify by calculating that

• 5 moles of CO₂ and 5 moles of H₂O do have the same mass.
• 240g of calcium and 240g of magnisium element have a mole ratio of 5:3.at mass H=1u ,Ca=40u,Mg=24u

1. The molecular mass of CaCO₃ is (40u +12u + 16× 3 u)

Hence the molecular mass is 100 u.

2. Mass of 1 mole of water is 18 g, Hence the mass of 5 mole of water is 90 g

Mass of 1 mole of CO2 is 44 g , 

∴ the mass of 5 moles of CO2 is 220 g

Hence the mass of 5 moles of water ≠ mass of 5 moles of carbon dioxide. 

3. Molar mass of calcium is 40 g per mole and the molar mass of magnesium is 24 g per moles.

number of moles of calcium = 240/ 40 

= 6 moles 

number of moles of magnesium = 240/ 24 

= 10 moles

Hence the mole ratio of Mg and calcium is 10:6 i.e. 5:3