posted by Min .
How many chlorine atoms are in 5.0 g of C2H3Cl3O2?
What mass of C2H3Cl3O2 would contain 1.0g Cl?
There are 6.02 x 10^23 atoms in a mole of anything. Calculate the molar mass of your compound, that mass will contain 6.02 x 10^23 molecules of that material (whatever it is), then calculate the number of molecules in 5.0 g of the material. The number of Cl atoms will be three times that because there are 3 Cl atoms in a mole of the material. After you do this, part b of your question should be apparent. If not, post your work and repost but tell us what you don't understand.