Calculate the mass of sugar and the volume of water required to prepare 70 g of a 2 percent solution.

m (substance) = m (solution) * w, which means:
m (sugar) = 70g * 0.02 = 1.4g – this is how much pure sugar is needed to prepare a solution
To find water, we simply subtract the mass of the solution from the mass of sugar:
m (water) = 70g-1.4g = 68.6g
Now this needs to be translated into volume:
V = Vm * n
n (water) = 68.6g / 18g / mol = 3.8mol
V (water) = 22.4 l / mol * 3.8 mol = 85.12 l