A solution contains 11% by mass of sodium chloride. This means that:

For every 100 grams of the solution, there are 11 grams of sodium chloride.

Here's how to break it down:

* Percent by mass is a way to express the concentration of a solution. It tells you the mass of the solute (the substance dissolved) as a percentage of the total mass of the solution (solute + solvent).

* 11% by mass means that 11 out of every 100 grams of the solution is made up of sodium chloride.

Example:

If you have 500 grams of this solution, you can calculate the mass of sodium chloride present:

* (11 grams NaCl / 100 grams solution) * 500 grams solution = 55 grams NaCl