The balanced chemical reaction is CaCO3(1mol)+2HCl(2mol)→CaCl2(1mol)+CO2+H2O.
0.0256 moles of calcium carbonate will react with 0.0512 mol HCl.
250 mL of 0.125 M HCl corresponds to 0.03125 moles. They react with 0.015625 mol calcium carbonate.
Hence, HCl is the limiting reagent.
Unreacted calcium carbonate is 0.0256−0.0156=0.01 mol =1.0 g.
The number of moles of calcium carbonate reacted is equal to the mole of calcium chloride formed.
Mass of calcium carbonate formed is 1.7344 g and nearest integer is 2.