OLD: Acids/Bases/Changes

1. Which is a characteristic property of acids?

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

2. Neutralization is a reaction between a(n)

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

3. The principle of conservation of mass is true

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

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

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

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

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

A) The total mass of the reactants is less than the total mass of the products.
B) The total mass of the reactants if greater 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) Exothermic reaction-physical change
B) Endothermic reaction-physical change
C) Phase Change-chemical change
D) Phase Change-physical change

8. What type of reaction does the flame represent?

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

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

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

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

A) a tree branch breaking
B) water freezing in a pond
C) steam rising from pavement
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) color change
B) physical change
C) chemical change
D) electromagnetic change

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

A) less than the total mass of the products.
B) unrelated to the total mass of the products.
C) exactly equal 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) mass change.
B) precipitate.
C) shape change.
D) a change in color.

14. An acid is a substance that

A) has pH lower than 7 and taste sour.
B) has a pH above 7 and tastes bitter.
C) turns red litmus paper blue.
D) has a pH above 7 and tastes 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 acidic environment.
B) It is most effective in a highly basic environment.
C) It is most effective in a slightly basic environment.
D) Is it most effective in a slightly acidic environment.

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

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

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

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

18. Which is an exothermic change?

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

19. Which of the following is a chemical change

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

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

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

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

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) A
C) B
D) C

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

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

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

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

27. Which substance would most neutralize an acidic food?

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

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 reactant.
C) a solvent.
D) a product.

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

A) very basic.
B) very acidic.
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) cheddar cheese
B) ham
C) apples
D) green beans

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

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

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

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

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