Count the total number of atoms in CaCO3: 2 3 4 5 6

6.2380 g

Explanation:

A mole of H2 molecules contains 6.023 x 10 (23) H2 molecules or 2 moles of H atoms (since each molecules has 2 atoms). A mole of CaCO3 (calcium carbonate) has one mole (Avogadro number) of Ca atoms, one mole of C atoms and 3 moles of O atoms.