Which of the following best describes when a mixture is considered to be a solution?

• A. When the components are uniformly distributed at the molecular level and form a single phase
• B. When the components can be separated by filtration
• C. When the mixture contains visible particles that settle over time
• D. When the mixture consists of two immiscible liquids

Answer: (A)

Verified step by step guidance

1. Understand the definition of a solution in chemistry: A solution is a homogeneous mixture where the solute is uniformly distributed within the solvent at the molecular or ionic level.
2. Recognize that in a solution, the components form a single phase, meaning there is no visible separation between different substances.
3. Contrast this with mixtures where components can be separated by physical means such as filtration, which indicates the presence of larger particles or heterogeneous mixtures.
4. Note that mixtures containing visible particles that settle over time are suspensions, not solutions, because the particles are not uniformly distributed.
5. Identify that mixtures of two immiscible liquids form separate layers (phases) and are not solutions because they do not mix uniformly at the molecular level.