Pretest for Teachers Chemistry Grade 7

I.  Choose the letter of the answer that best completes each statement.

1.  Matter that consists of two or more substances mixed together but not chemically combined is called a(n) ______.

A. element B. compound C. pure substance D. mixture

2.  In a solution, the ability of a substance to be dissolved is called the ______.

A. solvent B. solute C. solubility D. insoluble

3.  The simplest type of pure substance is a(n) ______.

A. compound B. alloy C. solution D. element

4.  The law of ______states that the mass of reactants before a chemical equation is equal to the mass of the products after the reaction in a closed system.

A. gravity B. conservation of mass C. matter D. substances

II. For questions 5-8, place an A (physical property) or B (chemical property) on the blank provided.

5. When exposed to oxygen, iron will rust ______

6. Dissolving salt ______

7. Paper is flammable.______

8. Gold is shiny.______

III.  Question 9 refers to the following diagram. The density of water is 1.0 g/cm3. The density of object A is 3.5 g/cm3 and the density of object B is 0.8 g/cm3.

A B

9a . Will object A float in water?______

9b. Will object B float in water? ______

9c. What is the formula in words to calculate density? ______

______

IV.  Chose the best answer for the following questions.

10.  A middle school science class is studying the effect of volume on the density of water. They conducted an investigation and constructed the following graph. What can you conclude from the data on the graph?

a.  As the density of water increases, its volume stays the same.

b.  As the volume of water increases, its density stays the same.

c.  As the volume of water increases, its density increases.

d.  As the density of water increases, its volume decreases.

11.  Which change will produce a new substance?

  1. Dissolve lemonade powder in water
  2. Burning a candle
  3. Heating water until it evaporates
  4. Stretching a rubber band

12.  A student believes that she has measured a new property that she did not learn in class. She calls her new property “X”. Here is a table of her property for different objects.

Object / Property X
Copper wire / 132 X
Copper spoon / 240 X
Glass jar / 89 X
Wooden block / 59 X

Based on her results, do you think that “X” is a property or not? Why?

a.  Yes, because all of the objects had different results.

b.  No, because all of the results were too similar.

c.  Yes, because all of the objects had similar results.

d.  No, because the objects made of the same substance had different results.

13.  What are the reactants in the following reaction?

carbon dioxide + water à carbonic acid

a.  water and carbon dioxide

b.  carbon and acid

c.  water and carbonic acid

d.  carbon dioxide and carbonic acid

14.  Your teacher mixes a liquid and a powder in a flask. The temperature of the mixture increases and a gas forms. Which of the following is a PRODUCT in the chemical reaction?

  1. The powder
  2. The liquid
  3. The gas
  4. The flask

15.  Which of the following is a mixture?

  1. Salt
  2. Salt water
  3. Water
  4. Lard

16. The Periodic Table is organized into metals and nonmetals. Circle the characteristic below that is not typical of most metals?

a. good conductor b. brittle c. malleable d. shiny

17. How does the Law of Conservation of Mass apply to a burning candle?

a. The amount of wax before the reaction equals the amount of energy afterwards.

b. The mass of the wick before the reaction equals the mass of the smoke afterwards.

c. The mass of the wick, wax that burned and the oxygen that helped the flame before the reaction equals the mass of the smoke and the gases released after the reaction.

d. The mass of the molecules of the candle before the reaction equals the mass of the candle and burned wick after the reaction.

18. When wood burns, a small amount of ashes is made. Why is the mass of the wood before the fire not equal to the mass of the ashes after the reaction?

a. The mass of the wood has been destroyed.

b. The mass of the wood and the oxygen that allowed it to burn will equal the mass of the ashes and the gas given off during the burning.

c. The mass of the wood and the ashes equals the mass of the oxygen and the smoke given off during the time that the wood burned.

d. The wood has holes in it so it is actually lighter in mass than it appears. The mass of just the wood will equal the mass of just the ashes after the burning.

V. Answer the following open ended questions.

19. A class conducted an experiment in which they mixed two colorless liquids. After

mixing the liquids, the students noticed bubbles and a gray solid that had formed at the bottom of the container.

  1. What kind of process occurred?
  1. Provide evidence supporting how you know this occurred.

20. Please refer to the following chemical reaction to answer these questions:

2Fe2O3 ® 4Fe + 3O2

Fill-in the Blank and Choose two from this list:

reactant, product, element, compound, mixture.

a. Fe2O3 is a ______and ______.

b.  During a chemical reaction, we started out with 20 grams of Fe2O3 and produced 15 grams of Fe. How many grams of O2 were produced? Calculate the mass of O2.

c.  Explain your answer to part b. above (explain using scientific words and your own words with evidence and reasoning)

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