Question

how does a pure substance differ from a mixture? check all that apply. * 2 points every sample of a given pure substance has exactly the same characteristic properties. every sample of a given pure substance has exactly the same composition. every sample of a given pure substance depends on the relative amount of the mixture’s components. every sample of a pure substance can be separated by physical means.

Explanation:

1. For the first option: Pure substances have uniform and fixed characteristic properties (like melting point, density) across all samples. So this is correct.
2. For the second option: A pure substance has a definite and constant composition (e.g., water is always \(H_2O\)). So this is correct.
3. For the third option: This describes a mixture (composition depends on component amounts), not a pure substance. So this is incorrect.
4. For the fourth option: Pure substances (elements or compounds) can't be separated by physical means (compounds need chemical methods, elements can't be separated further). Mixtures are separated by physical means. So this is incorrect.

Answer:

• Every sample of a given pure substance has exactly the same characteristic properties.
• Every sample of a given pure substance has exactly the same composition.