n(CaCO3)=m÷M
m being the mass of the sample and M being the molar mass of the compound; Molar mass is to be obtained by adding the atomic masses of all the elements in the compound.
therefore,
n(CaCO3)=m÷M
=28g÷100 g.mol
=0.28 mol
therefore, there are 0.28 moles in 28g of Calcium Carbonate.
