Answer: 4.1g
The law of conservation of mass saying that the mass can't be created or destroyed. That means the total weight of reactant should be equal to the total weight of the product. But, if the reaction creates a gas product, the gas produced could fly away and makes the product lighter. The mass of the CO2 that goes away in this reaction would be:
reactant=product
caco3 + HCL solution = CO2 + resulting solution
10g + 40.5g= CO2+ 46.4
CO2= 50.5g- 46.4g= 4.1g