Pure water:

Pure water:

• A. It is a pure substance with the same intrinsic properties throughout.
• B. It contains minerals
• C. It has a variable composition
• D. It is always acidic

Answer: (A)

A pure substance has a uniform composition and fixed properties throughout, so pure water is made only of water molecules (H2O) and exhibits the same intrinsic properties in any sample. Because there are no other substances dissolved or dispersed, its characteristic traits—like melting point, boiling point, density, and refractive index—are consistent everywhere in the sample. That’s why pure water is described as a pure substance with the same intrinsic properties throughout. If minerals were present, or if the composition varied by sample, you’d be dealing with a mixture or solution rather than a pure substance, which is why those options don’t fit. And while dissolved carbon dioxide can make water slightly acidic, pure water is not defined as always acidic; its typical state is neutral (though small deviations can occur in real environments).

A pure substance has a uniform composition and fixed properties throughout, so pure water is made only of water molecules (H2O) and exhibits the same intrinsic properties in any sample. Because there are no other substances dissolved or dispersed, its characteristic traits—like melting point, boiling point, density, and refractive index—are consistent everywhere in the sample. That’s why pure water is described as a pure substance with the same intrinsic properties throughout.

If minerals were present, or if the composition varied by sample, you’d be dealing with a mixture or solution rather than a pure substance, which is why those options don’t fit. And while dissolved carbon dioxide can make water slightly acidic, pure water is not defined as always acidic; its typical state is neutral (though small deviations can occur in real environments).