Acompound composed of sulfur and fluorine is found to contain 62.79% by mass of sulfur. if the approximate molar mass of this compound is 102.13 g/mol, what is its molecular formula?

Let our basis for answering this item be 1 mol of the given substance. Then, we calculate for the equivalent mass by multiplying the number of moles with the molar mass.
                  mass = (102.13 g/mol)(1 mol) = 102.13 g of substance

Then, we calculate for the amount of sulfur and fluorine each using the percentage given.
     sulfur = (0.6279)(102.13 g) = 64.13 g of sulfur
     fluorine = (1 - 0.6279)(102.13 g) = 38 g of fluorine

Then, calculate for the number of moles of the sulfur and fluorine by dividing the calculated mass by the molar mass of each.
     moles of sulfur = (64.13 g)(1 mol/32 g) = 2 mols suflur
     moles of fluorine = (38 g)(1 mol/19 g) = 2 mols fluorine

The molecular formula of the substance is S₂F₂. 

ANSWER: S₂F₂

B.1 - hydrogren-1 can only mean there is 1 neutron. it's obvious there is 1 proton or else it wouldn't be hydrogen, so they wouldn't put a number after it unless they were indicating the number of neutrons