Which statement best describes a solution of sodium chloride in water?

• A. It is a pure substance composed only of NaCl.
• B. It is a homogeneous mixture in which NaCl is uniformly dissolved in H2O.
• C. It is a heterogeneous mixture where NaCl settles at the bottom.
• D. It is a colloidal suspension of NaCl particles in water.

Answer: (B)

Verified step by step guidance

1. Understand the nature of the components involved: sodium chloride (NaCl) is an ionic compound, and water (H2O) is a polar solvent.
2. Recall that when NaCl dissolves in water, it dissociates into its ions (Na\textsuperscript{+} and Cl\textsuperscript{-}), which become uniformly distributed throughout the water.
3. Recognize that a solution where the solute (NaCl) is completely dissolved in the solvent (water) and is uniform throughout is called a homogeneous mixture.
4. Differentiate this from a pure substance, which consists of only one type of particle, and from heterogeneous mixtures, where components are not uniformly distributed and may separate over time.
5. Conclude that the best description of a sodium chloride solution in water is a homogeneous mixture with NaCl uniformly dissolved in H2O.