This problem is quite easy once you start thinking about it.
If the empirical formula is HgCl (which has a molar mass of 271.5 g/mol)
And the molar mass of the molecular compound is 472.2 g/mol, just divide the two numbers. You'll get 1.74. And since this number is a decimal, this question isn't solvable. You've either provided the wrong empirical formula or the wrong molar mass.
