I believe it to be g/mol of Calcium carbonate because to finde mass...u must have grams(g) as units.... it is the only one that have g as units
as for the first answer the avogadros number gives u the number of atoms in one mole of calcium carbonate.... the second one is based on ... At s.t.p one mole of gas occupies 22.4 dm³⇒to find volume
