To 100 g of a 20% sugar solution, 400 cm3 of water was added. Calculate the percentage of sugar in the resulting solution.

m1 = 100 g.
W1 = 20%.
V (H2O) = 400 cm ^ 3.
p (H2O) = 1 g / cm ^ 3.
Determine the percentage of sugar in the resulting solution. We write down the solution.
1. Find the mass of salt in the original solution.
W = mr.w / mr-ra × 100%.
m r.v = 100 × 20/100 = 20 g.
2. Find the mass of water.
m = V × p.
m = 400 cm ^ 3 × 1 g / cm ^ 3 = 400 g.
3. Find the mass of the solution.
m p-pa = m (p – pa) + m (H2O) = 100 g + 400 g = 500 g.
4. Find the percentage of sugar in the resulting solution.
W = 20/500 × 100 = 4%.
This means that the resulting solution contains 4% sugar.
Answer: W = 4%.