To 40 g of a 10% solution of sodium chloride poured 60 g of water, the mass fraction of the substance in the solution.

Table salt formula: NaCl.
-Let’s find the mass of the solute of common salt in its solution. To do this, multiply the mass fraction of table salt by the mass of the solution and divide by one hundred percent: 40 * 10/100 = 4g.
– Since water was poured in, and not a solution of sodium chloride, only the mass of the solution changes. The mass of the solute remains unchanged.
-The mass of the solution after adding water is: 40 + 60 = 100g.
– Mass fraction of sodium chloride in the resulting solution: W = 4/100 * 100 = 4% – the answer.