To prepare the solution, 10 g of sodium chloride was placed in 190 g of water. Find the mass fraction of salt in the resulting solution.

The mass fraction of a substance in a solution is the ratio of the mass of the solute to the mass of the solution.
In our case, after the dissolution of common salt, the mass of the solution will be equal to the sum of the mass of water and the mass of salt, that is: 190 + 10 = 200 grams.
The mass fraction of salt will be equal to: 10/200 = 1/20 part. To determine the mass fraction in percent, the resulting value must be multiplied by 100%. We get: 1/20 x 100% = 5%.
Answer: the mass fraction of salt in the solution will be 1/20 or 5%.