To calculate the number of moles present in 4 grams of CaCO3, you need to know the atomic masses of calcium, carbon, and oxygen. These can be found on the periodic table and are:
Ca: 40 g/mol
C: 12 g/mol
O: 16 g/mol
To find the number of moles of CaCO3, you need to add the number of moles of each element present in the compound. In this case, CaCO3 contains 1 mole of calcium, 1 mole of carbon, and 3 moles of oxygen.
The total number of moles in 4 grams of CaCO3 can be calculated by dividing the mass of the compound by its molar mass. The molar mass of CaCO3 is equal to the sum of the atomic masses of its constituent elements, or 40 g/mol + 12 g/mol + 3 * 16 g/mol = 100 g/mol.
Therefore, the number of moles in 4 grams of CaCO3 is 4 g / 100 g/mol = <<4/100=0.04>>0.04 moles.
So there are 0.04 moles of CaCO3 present in 4 grams of the compound.