Question: how many grams of chlorine are present in three molecules of carbon tetrachloride (ccl4)?
Answer: One molecule of CCl4 has 1 carbon atom and 4 chlorine atoms. The atomic weight of carbon is 12.01 and the atomic weight of chlorine is 35.45. So the molecular weight of CCl4 is 12.01 + 4*35.45 = 153.81 g/mol. The number of molecules in a mole of any given substance is always the same: 6.022 x 10^23.