After growing 40 g of the solution, 10 g of salt remains. Determine the mass fraction of the dissolved salt in the solution.

Given:
m solution (salt) = 40 g
m (salt) = 10 g

Find:
ω (salt) -?

1) Evaporation – the process of removing a solvent from a solution;
2) Calculate the mass fraction of dissolved salt in the solution:
ω (salt) = m (salt) * 100% / m solution (salt) = 10 * 100% / 40 = 25%.

Answer: The mass fraction of dissolved salt is 25%.