An unknown molecule contains only carbon and sulfur, and it is 15.77% carbon by mass. what is the molecular geometry of this molecule?

We take as a basis for solving this item, 100 g of sample. If 15.77% of the sample is carbon, we solve for the amount of carbon in the sample,

    Carbon = (100 g)(0.1577)  = 15.77

Then, we solve for the amount sulphur in the sample by,

    Sulfur = (100 g)(1 – 0.1577) = 84.23 g

 Next, we solve for the number of moles of the elements by dividing the calculated masses by the molar mass.

 Carbon = (15.77g)(1 mol/12 g) = 1.3 moles

 Sulphur = (84.23 g)(1 mol/32 g) = 2.63 moles

 From the ratio of the calculated number of moles, we can say that each mol of carbon will have to be paired up with two other sulphur atoms. Thus, the shape of the molecule is LINEAR. 

icc, international association for cereal chemistry