Mr(CaCO3) = Ar(Ca) + Ar(C) + 3Ar(O) = 40 + 12 + 3 * 16 = 100
Mr(BaSO4) = Ar(Ba) + Ar(S) + 4Ar(O) = 137 + 32 + 4 * 16 = 233
Mr(CO2) = Ar(C) + 2Ar(O) = 12 + 2 * 16 = 44
Mr(C6H12O6) = 6Ar(C) + 12Ar(H) + 6Ar(O) = 6 * 12 + 12 * 1 + 6 * 16 = 180
