Question

Given:
1 atom of potassium, 1 atom of chlorine, varying numbers of oxygen atoms
Determine mass percent of oxygen
Calculate relative numbers of oxygen atoms
Compound decomposes when heated (oxygen=gas, Kcl=solid)
Mass of test tube = 19.85g
Mass of test tube + original compound = 24.62g
mass of test tube + potassium chloride residue = 22.83

** I need help with numbers 3, 4, and 5
1) Calculate mass of original compound
2) Calculate mass of potassium chloride residue produced
3) Calculate mass of oxygen lost as gas
4) Calculate mass percent of oxygen in original compound, based on experimental data
5) Determine whether or not your compound contains 1,2,3, or4 oxygen atoms by calculating mass percent of oxygen for each possible compounds
6) Calculate percentage error using the difference between theoretical mass percent of oxygen and the mass measured in experiment