Final answer:
When salt is added to water and dissolves completely, the mixture becomes homogeneous, meaning that the composition is uniform throughout the mixture.
Step-by-step explanation:
If salt is added to water, the resulting mixture is known as a homogeneous mixture, or a solution. This is because, once the salt dissolves, the composition is uniform throughout, and it acts as if it were a single substance. Even if the concentration of salt varies from one sample to another, within a given sample, the dissolved salt is evenly distributed throughout the entire salt water sample. This is in contrast to a heterogeneous mixture, where the different components are not uniformly distributed.
For instance, if table salt (NaCl) is mixed into water (H₂O) and dissolves completely, the two substances intermingle at the molecular level, resulting in a clear solution that appears to be a single substance. Thus, saltwater is an example of a homogeneous mixture or a solution. By contrast, a combination of salt mixed with pepper would be a heterogeneous mixture because the particles of each substance would remain distinct.