I had a multiple choice question like this: Which one of these CANNOT determine the molar mass? a) osmotic pressure b)change in temperature of freezing point c)vapor pressure measurements d)specific heat e)density of solid I know its not a or b. However i cannot decide between c, d, or e.... I had d as well because you cannot determine the molar mass for everything. According to petit-dulong law, it only applies to metal elements. And even still, you cannot really determine the molar mass directly(can only estimate), where as osmotic pressure you can find molar mass directly and precise if values are correct. please help thanks.