5.97 g of a gaseous compound, comprised of only the elements carbon and fluorine, is analyzed and found to con

Question

5.97 g of a gaseous compound, comprised of only the elements carbon and fluorine, is analyzed and found to contain 1.43 g of carbon.
A 285-mL sample of the gas has a mass of 1.27 g at STP.
Enter the molecular formula of the compound.

I have no clue to go about this problem. A little help with an explanation would be nice =D

Answer 1

If 285 ml of the compound has a certain mass, you can work out the mass of 22,400 ml, which will give you the Mr of the compound.

Subtract 1.43 from 5.97 to get the mass of F. Now divide the mass of F by 19, and the mass of C by 12. Scale this up to a whole-number ratio, and work out what the Mr now appears to be. It should be a simple fraction of the answer to the Mr you worked out first, and so you can now write down the molecular formula.