Which compound has the highest sulfur content by mass S2Cl2 or Na2SO3?

The amount of sulfur content is the mass of sulfur in the compound divided by the total mass of the compound and since this is often taken as a percentage, you multiply by 100.

So what you do is:
1. Find the mass of sulfur in the compound using the molecular formula and the relative atomic mass of sulfur.
2. Find the molecular mass of the compound.
3. Find the percentage.
4. Compare the percentage, the one with the higher percentage contains the higher sulfur content.

Post what you get! :)