An aqueous solution of potassium sulfate, K2SO4, contains 3.28 grams of potassium sulfate and 17.7 grams of water.

The percentage by mass of potassium sulfate in the solution is
%.

I think the correct answer from the choices listed above is the first option. The Curies conclude about radioactivity based on their studies that the amount of radioactivity is an extensive property because it varies as the amount of material varies. Hope this answer the question. Have a nice day.