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Multiple Choice
Open Response

2. Use the figure below to answer question 1.

3. 1. The picture above shows a light stick
1. The picture above shows a light stick. Light sticks begin to glow when the vial inside the stick is broken. Chemicals inside the vial mix with chemicals outside of the vial. Which of the following statements BEST supports the idea that a chemical reaction, rather than a physical change, is occurring?
A The vial is broken into smaller pieces.
B Energy is released in the form of light.
C Two different substances are combined.
D The substances are in a flexible container.

4. 1. The picture above shows a light stick
1. The picture above shows a light stick. Light sticks begin to glow when the vial inside the stick is broken. Chemicals inside the vial mix with chemicals outside of the vial. Which of the following statements BEST supports the idea that a chemical reaction, rather than a physical change, is occurring?
A The vial is broken into smaller pieces.
B Energy is released in the form of light.
C Two different substances are combined.
D The substances are in a flexible container.

5. 2. Which chemical equation best illustrates the law of conservation of mass?
A by the gravitational attraction between molecules
B by the bumping of one molecule into another molecule
C by one molecule sending out electricity to another molecule
D by one molecule sending out heat waves to another molecule

6. 2. Which chemical equation best illustrates the law of conservation of mass?
A by the gravitational attraction between molecules
B by the bumping of one molecule into another molecule
C by one molecule sending out electricity to another molecule
D by one molecule sending out heat waves to another molecule

7. 3. Some spoons are made with the element silver (Ag)
3. Some spoons are made with the element silver (Ag). Over time, these spoons will turn black if they are not cleaned with a special solution. Which of the following statements BEST explains why the element silver in the spoons turns black?
A It absorbs energy when exposed to warm food.
B It breaks down into smaller and smaller particles.
C It reacts with substances in the air to form a new substance.
D It changes from one phase of matter into another phase of matter.

8. 3. Some spoons are made with the element silver (Ag)
3. Some spoons are made with the element silver (Ag). Over time, these spoons will turn black if they are not cleaned with a special solution. Which of the following statements BEST explains why the element silver in the spoons turns black?
A It absorbs energy when exposed to warm food.
B It breaks down into smaller and smaller particles.
C It reacts with substances in the air to form a new substance.
D It changes from one phase of matter into another phase of matter.

9. 4. Which of the following contains one oxygen atom?
A H2O
B CO2
C 2N2O
D Co

10. 4. Which of the following contains one oxygen atom?
A H2O
B CO2
C 2N2O
D Co

11. 5. Which process causes substances to react to form one or more new substances?
A chemical change
B physical change
C evaporation
D freezing

12. 5. Which process causes substances to react to form one or more new substances?
A chemical change
B physical change
C evaporation
D freezing

13. Use the graph below to answer question 6.

14. 6. The graph above shows the change in temperature over time in a chemical reaction. According to the graph, how would this reaction be described?
A endothermic
B exothermic
C unbalanced
D combustion

15. 6. The graph above shows the change in temperature over time in a chemical reaction. According to the graph, how would this reaction be described?
A endothermic
B exothermic
C unbalanced
D combustion

16. 7. Which chemical equation correctly shows the formation of water from hydrogen and oxygen?
A H2  O2  H2O
B 2H2  O2  2H2O
C H2  2O  H2O
D H  O2  H2O

17. 7. Which chemical equation correctly shows the formation of water from hydrogen and oxygen?
A H2  O2  H2O
B 2H2  O2  2H2O
C H2  2O  H2O
D H  O2  H2O

18. 8. A scientist carries out a reaction in a test tube
8. A scientist carries out a reaction in a test tube. After the bubbling stops, she notices that the test tube is very warm. What might she conclude about the reaction?
A The reaction happened very quickly.
B The reaction is endothermic.
C The reaction is exothermic.
D No reaction took place.

19. 8. A scientist carries out a reaction in a test tube
8. A scientist carries out a reaction in a test tube. After the bubbling stops, she notices that the test tube is very warm. What might she conclude about the reaction?
A The reaction happened very quickly.
B The reaction is endothermic.
C The reaction is exothermic.
D No reaction took place.

20. 9. A substance that is used to speed up a chemical reaction is called
A a reactant.
B an inhibitor.
C a precipitate.
D a catalyst.

21. 9. A substance that is used to speed up a chemical reaction is called
A a reactant.
B an inhibitor.
C a precipitate.
D a catalyst.

22. 10. During a laboratory experiment, Tran applied the law of conservation of energy. Which of the following did he assume to be true?
A Energy is not changed.
B Energy is not created or destroyed.
C The total energy of the reactants is greater than the total energy of the products.
D The total energy of the reactants is less than the total mass of the products.

23. 10. During a laboratory experiment, Tran applied the law of conservation of energy. Which of the following did he assume to be true?
A Energy is not changed.
B Energy is not created or destroyed.
C The total energy of the reactants is greater than the total energy of the products.
D The total energy of the reactants is less than the total mass of the products.

24. Open Response
11. Identify all reactants and products in the following chemical reaction.
CaCl2 + AgNO3  AgCl + Ca(NO3)2

25. 11. Identify all reactants and products in the following chemical reaction.
CaCl2 + AgNO3  AgCl + Ca(NO3)2
Full-credit answers should have all of the following identified: The reactants are the CaCl2 (calcium chloride) and AgNO3 (silver nitrate). The products are the AgCl (silver chloride) and Ca(NO3)2 (calcium nitrate).

26. 12. Compare synthesis and decomposition reactions, and give an example of each.

27. 12. Compare synthesis and decomposition reactions, and give an example of each.
Full-credit answers should include the following points:
• In a synthesis reaction, two or more substances combine to form a new compound.
• In a decomposition reaction, a compound breaks down into two or more simpler substances.
• Examples may vary. The example of a synthesis reaction in the student book is when sodium reacts with chlorine to produce sodium chloride. The example of a decomposition reaction in the student book is carbonic acid breaking down into water and carbon dioxide.