Calculate the percentage by weight of a solution of 400 grams of sulfuric acid (H2SO4) in a solution with 4 liters of water.

Answer 1

As with your previous question, we would need the density of the solution. I'm believing that the asker of these questions meant to ask for the % (w/v) which is different than % by weight. Percent w/v is mass of solute per 100 mls of solvent, not per 100 g of solvent. I'll answer this question as % weight/volume.

400 g / 4000 mls = 0.1 g / ml x 100 mls = 10 g / 100 mls = 10% (w/v)