What percentage of the m of a sulfuric acid molecule,h2so is sulfur?

First off, the chemical formula for sulfuric acid is H2SO4, not H2SO. Now that we've established that you find the percent by dividing the molar m of the element you're looking for by the molar m of the compound and multiply by 100. Molar m of hydrogen is 1, sulfur is 32.1, and oxygen is 16 so the molar m of the compound is 98.1 grams. I don't feel like getting a calculator out to do the on work for you, but off the top of my head, that's about 33%.