When you add salt to distilled water, the density of the solution increases. Here's why:

* Salt dissolves: Salt (NaCl) dissolves in water, meaning the salt crystals break down into individual sodium (Na+) and chloride (Cl-) ions.

* Increased mass in the same volume: These ions now occupy the same volume of water as the original water molecules. Since the ions have mass, the total mass of the solution increases.

* Density = Mass/Volume: Since the mass increases while the volume remains relatively constant, the density (mass per unit volume) of the solution increases.

In summary: Adding salt to distilled water results in a higher density solution because the salt ions contribute to the overall mass without significantly changing the volume.