CHAPTER 2 Assessment

Reviewing Content

Choose the letter that best answers the question or completes the statement.

1. Which of these substances is not an element?

   • water

   • hydrogen

   • aluminum

   • iron

2. Tap water is

   • an element.

   • a compound.

   • a substance.

   • a mixture.

3. When a homemade oil-and-vinegar salad dressing is left standing, it separates into layers. The salad dressing is a

   • solution.

   • suspension.

   • colloid.

   • compound.

4. Which of the following is not an example of a physical property?

   • density

   • flammability

   • hardness

   • melting point

5. Which material is a poor conductor of heat?

   • iron

   • silver

   • wood

   • copper

6. A material that can be hit without shattering is

   • viscous.

   • flammable.

   • malleable.

   • hard.

7. At room temperature, a substance with a melting point of 40ºC is a

   • solid.

   • liquid.

   • gas.

   • mixture.

8. Which action involves a chemical change?

   • making ice cubes

   • adding sugar to tea

   • cutting wrapping paper

   • baking a cake

9. A substance that has little tendency to change into other substances is said to have low

   • reactivity.

   • density.

   • viscosity.

   • conductivity.

10. Formation of a precipitate is usually evidence of

    • the separation of a mixture.

    • a chemical change.

    • the formation of a mixture.

    • a physical change.

Understanding Concepts

11. Explain why the properties of a pure substance do not vary from sample to sample.

12. What is the difference between an element and a compound?

13. How does the composition of a mixture of hydrogen and oxygen differ from the composition of a compound containing hydrogen and oxygen?

14. Suppose all the grains in a sample of sand were exactly the same size. Could the sample still be a heterogeneous mixture? Explain your answer.

15. What allows a mixture to be separated by filtration?

16. Explain why viscosity is classified as a physical property.

17. Based on these pieces of pottery found in Grand Canyon National Park, would yo describe pottery as a malleable or brittle material?

    

18. A sample of copper can be drawn into a thin wire. Is this property of copper a physical property or a chemical property? Explain.

19. Name one physical property and one chemical property of wood.

20. Why is breaking down a compound into its elements considered a chemical change?

21. List one physical change and one chemical change that occur when a candle burns.

22. Suppose yo need to identify the material in an object without changing the object in any way. Should yo use physical or chemical properties to identify the material? Explain your choice.

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