How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an excess of sulfuric acid?

The entire process, assuming their degrees of ionization to be 1 due to their strong acid/base properties, should be

2NaOH + H2SO4 - - > 2H2O + Na2SO4

Therefore, if 200 grams of sodium hydroxide are used with molar mass 40, than 5 mols of sodium hydroxide was used. Using the ratio of 2:1:2:1, we see that 2.5 mols of Na2SO4 was used, therefore 2.5*molar mass = 2.5*142 = 355 grams.