Which of the following is NOT true about mixtures?

• A. The components of a mixture retain their individual properties.
• B. Mixtures always have a fixed composition.
• C. Mixtures can be either homogeneous or heterogeneous.
• D. Mixtures can be separated into their components by physical means.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the definition of a mixture. A mixture is a combination of two or more substances where each substance retains its own chemical identity and properties.
2. Step 2: Recognize that mixtures do not have a fixed composition. The proportions of components in a mixture can vary, unlike compounds which have a fixed ratio of elements.
3. Step 3: Identify that mixtures can be classified as homogeneous (uniform composition throughout) or heterogeneous (non-uniform composition).
4. Step 4: Recall that mixtures can be separated into their individual components by physical methods such as filtration, distillation, or chromatography, because the components retain their physical properties.
5. Step 5: Conclude that the statement 'Mixtures always have a fixed composition' is NOT true, since mixtures can have variable compositions.