Can someone help me to answer this correctly, please, and explain it. Please answer these 2 short questions, I don't have more money to buy more questions. These 2 questions are different.

1. a.

1. b.

A student has 530.0mL of a 0.1003M aqueous solution of Na2SO4 to use in an experiment. He accidentally leaves the container uncovered and comes back the next week to find only a solid residue. The mass of the residue is 17.13g. Determine the chemical formula of this residue. If the substance is a hydrate, use a period instead of a dot in its formula. A solution is made by dissolving 17.3g of silver acetate, AgCH3COO, in enough water to make exactly 500 . mL of solution. Calculate the molarity of each species: AgCH3COOmol/LAg+mol/LCH3COOmol/L