OLD: Acids/Bases/Changes - חִידוֹן

1. Which is a characteristic property of acids?

A) They turn red litmus paper blue.
B) They turn blue litmus paper red.
C) They do not react with metals.
D) They taste bitter.

2. Neutralization is a reaction between a(n)

A) acid and a base.
B) salt and water.
C) acid and a metal.
D) base and a salt.

3. The principle of conservation of mass is true

A) for reactions in both open and closed systems.
B) only for reactions that take place in closed systems.
C) only for reactions that take place in open systems.
D) for no reactions at all.

4. In terms of pH, explain what would happen if you mixed vinegar with a solution of ammonia?

A) the pH level of the folution would be less than 3
B) the substances would not mix, and you could still take two different pH readings
C) the pH level of the solution would be more than 12
D) the pH level of the solution would be between 3 and 11

5. Use the pH scale to compare an apple and a lemon.

A) The apple and lemon have the same pH level.
B) The lemon has a higher pH than the apple.
C) The apple has a lower pH than the lemon.
D) The lemon has a lower pH than the apple.

6. In chemical reactions, what does the principle of conservation of mass mean?

A) The total mass of the reactants if greater than the total mass of the products.
B) The total mass of the reactants is less than the total mass of the products.
C) Matter is not changed.
D) Matter is not created or destroyed.

7. When the candle was lit, a pool of liquid wax formed in the area around the wick, and then spilled over the side and solidified. What type of change is occurring in terns of the wax ONLY?!

A) Endothermic reaction-physical change
B) Phase Change-physical change
C) Phase Change-chemical change
D) Exothermic reaction-physical change

8. What type of reaction does the flame represent?

A) endothermic reaction-physical change
B) Exothermic reaction-chemical change
C) exothermic reaction-physical change
D) endothermic reaction-chemical change

9. Which of these properties of an iron nail is a physical property?

A) has a long narrow shape with a smooth texture
B) rusts
C) does not burn when a flame is applied
D) reacts with hydrochloric acid to release hydrogen gas

10. Which of the following examples in nature represents a chemical change?

A) steam rising from pavement
B) water freezing in a pond
C) a tree branch breaking
D) a tree burning after a lightning strike

11. On a cold morning, Fawn awoke to find frost on her bedroom windows. Which type of process is the formation of frost?

A) chemical change
B) electromagnetic change
C) physical change
D) color change

12. In a chemical reaction, the total mass of the reactants is

A) less than the total mass of the products.
B) exactly equal to the total mass of the products.
C) unrelated to the total mass of the products.
D) greater than the total mass of the products.

13. The best evidence for a chemical reaction is

A) shape change.
B) precipitate.
C) a change in color.
D) mass change.

14. An acid is a substance that

A) has a pH above 7 and tastes bitter.
B) turns red litmus paper blue.
C) has a pH above 7 and tastes sour.
D) has pH lower than 7 and taste sour.

15. Pepsin is an enzyme found in the stomach that breaks down proteins. The pH in the stomach is about 2. Which statement best describes pepsin?

A) It is most effective in a highly basic environment.
B) It is most effective in a slightly basic environment.
C) Is it most effective in a slightly acidic environment.
D) It is most effective in a highly acidic environment.

16. Which of the following is a chemical property of a substance?

A) conductivity
B) reactivity
C) the ability to reflect light
D) melting point

17. Which of the following is an example of a physical change?

A) melting
B) corroding
C) rusting
D) burning

18. Which is an exothermic change?

A) coal burning
B) frying an egg
C) ice melting
D) water turning into steam

19. Which of the following is a chemical change

A) toasting a marshmallow
B) melting ice
C) boiling water
D) breaking a toothpick in half

20. Which of the following is formed when two elements combine chemically?

A) an electron
B) a mixture
C) a compound
D) an atom

21. A log burned and became a pile of ashes. The mass of the ashes was less than the mass of the log before it burned. What can you conclude based on the law of conservation of mass?

A) The chemical reaction destroyed matter.
B) Not all of the products and reactants could be measured because the chemical reaction took place in an open system.
C) The chemical reaction created matter.
D) The chemical reaction did not work as expected because it took place in a closed system.

22. When baking soda mixes with vinegar, the solution feels cool. This temperature change is an indication that

A) energy is being absorbed by the reaction.
B) no reaction is taking place.
C) matter is being released.
D) an exothermic reaction is occuring.

23. The circles and dots represent atoms of two different elements. Atoms touching each other are considered bonded to each other. Which box contains a mixture?

A) D
B) B
C) C
D) A

24. Which of the following is formed when two elements combine but no chemical bonds are broken or formed?

A) an electron
B) a mixture
C) an atom
D) a compound

25. Electron dot diagrams for sodium and chlorine are shown. How does sodium and chlorine bond together to make a stable compound?

A) Sodium gains one electron and chlorine loses on electron.
B) Sodium gains seven electrons and chlorine loses seven electrons.
C) Sodium loses one electron and chlorine gains one electron.
D) Sodium loses seven electrons and chlorine gains seven electrons.

26. Monica made snack for her friends by putting pretzels, peanuts, and raisins together in a bowl. Which statement describes Monica's snack?

A) It is a new element because a chemical change took place.
B) It is a mixture because each ingredient kept its original properties.
C) It is a solution because the ingredients cannot be separated.
D) It is a new chemical compound because a physical change took place.

27. Which substance would most neutralize an acidic food?

A) Baking Soda (pH 8-9)
B) Water (pH 6-7)
C) Dairy (pH 5-7)
D) Citrus Fruit (pH 2-3)

28. A teaspoon of dry coffee crystals dissolves when mixed in a cup of hot water. This process produces a coffee solution. The original crystals are classified as

A) a solute.
B) a product.
C) a solvent.
D) a reactant.

29. The table shows the pH and reaction of litmus of four body fluids. The data indicate that gastric juice is

A) very acidic.
B) very basic.
C) positively charged.
D) negatively charged.

30. The table shows pH values of some foods. A patient has chronic indigestion due to an overproduction of stomach acid. Which foods should the patient avoid until the condition is resolved?

A) green beans
B) ham
C) apples
D) cheddar cheese

31. Solutions and colloids are both similar in that both are

A) a mixture.
B) a solvent.
C) a solute.
D) a suspension.

32. A compound that changes color when it comes into contact with an acid or a base is a(n):

A) indicator
B) base
C) acid
D) litmus paper

33. True/False. This was the Unit 2 test and it was like the Study Guide in your notebook.

A) True
B) False

34. Is this situation showing a chemical or physical change?

A) Physical change because a new substance formed.
B) Chemical change because the mass stayed the same.
C) Chemical change because a precipitate formed.
D) Physical change because a precipitate formed..

35. True/False. The Law of Conservation is shown in this diagram.

A) False
B) True

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OLD: Mixtures

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