Chemistry answers

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Chemistry answers

Chemistry

AP Chemistry

Study Guide

1. According to the law of multiple proportions:

A) if the same two elements form two different compounds, they do so in the same ratio.

B) it is not possible for the same two elements to form more than one compound.

C) the ratio of the masses of the elements in a compound is always the same.

D) the total mass after a chemical change is the same as before the change.

E) none of these

2. Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

A) NH₄ and NH₄Cl

B) ZnO₂ and ZnCl₂

C) H₂O and HCl

D) NO and NO₂

E) CH₄ and CO₂

3. Many classic experiments have given us indirect evidence of the nature of the atom. Which of the experiments listed below did not give the results described?

A) The Rutherford experiment proved the Thomson "plum-pudding" model of the atom to be essentially correct.

B) The Rutherford experiment was useful in determining the nuclear charge on the atom.

C) Millikan's oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron.

D) The electric discharge tube proved that electrons have a negative charge.

4. Which of the following statements from Dalton's atomic theory is no longer true, according to modern atomic theory?

A) Elements are made up of tiny particles called atoms.

B) Atoms are not created or destroyed in chemical reactions.

C) All atoms of a given element are identical.

D) Atoms are indivisible in chemical reactions.

E) All of these statements are true according to modern atomic theory.

5. The first people to attempt to explain why chemical changes occur were

A) alchemists.

B) metallurgists.

C) physicians.

D) physicists.

E) the Greeks.

6. The Greeks proposed that matter consisted of four fundamental substances:

A) fire, earth, water, air

B) fire, metal, water, air

C) earth, metal, water, air

D) atoms, fire, water, air

E) atoms, metal, fire, air

7. The first chemist to perform truly quantitative experiments was

A) Paracelsus.

B) Boyle.

C) Priestly.

D) Bauer.

E) Lavoisier.

8. The scientist who discovered the law of conservation of mass and is also called the father of modern chemistry is

A) Proust.

B) Boyle.

C) Priestly.

D) Bauer.

E) Lavoisier.

9. Which of the following pairs can be used to illustrate the law of multiple proportions?

A) SO and SO₂

B) CO and CaCo₃

C) H₂O and C₁₂H₂₂O₁₁

D) H₂SO₄ and H₂S

E) KCl and KClO₂

10. The chemist credited for inventing a set of symbols for writing elements and a system for writing the formulas of compounds (and for discovering selenium, silicon, and thorium) is

A) Boyle.

B) Lavoisier.

C) Priestly.

D) Berzelius.

E) Dalton.

11. What element (in trace amounts) has been shown to help in protecting against heart disease and cancer?

A) silicon

B) oxygen

C) selenium

D) copper

E) potassium

12. The first scientist to show that atoms emit any negative particles was

A) J. J. Thomson.

B) Lord Kelvin.

C) Ernest Rutherford.

D) William Thomson.

E) John Dalton.

13. The scientist whose alpha-particle scattering experiment led him to conclude that the nucleus of an atom contains a dense center of positive charge is

A) J. J. Thomson.

B) Lord Kelvin.

C) Ernest Rutherford.

D) William Thomson.

E) John Dalton.

14. Which one of the following statements about atomic structure is false?

A) The electrons occupy a very large volume compared to the nucleus.

B) Almost all of the mass of the atom is concentrated in the nucleus.

C) The protons and neutrons in the nucleus are very tightly packed.

D) The number of protons and neutrons is always the same in the neutral atom.

E) All of the above statements (a-d) are true.

15. If the Thomson model of the atom had been correct, Rutherford would have observed

A) alpha particles going through the foil with little or no deflection.

B) alpha particles greatly deflected by the metal foil.

C) alpha particles bouncing off the foil.

D) positive particles formed in the foil.

E) None of the above observations is consistent with the Thomson model of the atom.

16. Rutherford's experiment was important because it showed that:

A) radioactive elements give off alpha particles.

B) gold foil can be made to be only a few atoms thick.

C) a zinc sulfide screen scintillates when struck by a charged particle.

D) the mass of the atom is uniformly distributed throughout the atom.

E) an atom is mostly empty space.

17. Which of the following name(s) is(are) correct?

1. sulfide S^2–

2. ammonium chloride NH₄Cl

3. acetic acid HC₂H₃O₂

4. barium oxide BaO

A) all

B) none

C) 1, 2

D) 3, 4

E) 1, 3, 4

18. Which of the following atomic symbols is incorrect?

19. The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

A) 75 protons, 75 neutrons.

B) 75 protons, 130 neutrons.

C) 130 protons, 75 neutrons.

D) 75 protons, 110 neutrons.

E) not enough information is given.

20. Which statement is not correct?

A) The mass of an alpha particle is 7300 times that of the electron.

B) An alpha particle has a 2+ charge.

C) Three types of radioactive emission are gamma rays, beta rays, and alpha particles.

D) A gamma ray is high-energy light.

E) There are only three types of radioactivity known to scientists today.

21. has

A) 20 protons, 20 neutrons, and 18 electrons.

B) 22 protons, 20 neutrons, and 20 electrons.

C) 20 protons, 22 neutrons, and 18 electrons.

D) 22 protons, 18 neutrons, and 18 electrons.

E) 20 protons, 20 neutrons, and 22 electrons.

24. All of the following are true except:

A) Ions are formed by adding electrons to a neutral atom.

B) Ions are formed by changing the number of protons in an atom's nucleus.

C) Ions are formed by removing electrons from a neutral atom.

D) An ion has a positive or negative charge.

E) Metals tend to form positive ions.

25. Which of the following statements is (are) true?

A) have the same number of neutrons.

B) are isotopes of each other because their mass numbers are the same.

C) .

D) a and b

E) a and c

26. Which among the following represent a set of isotopes? Atomic nuclei containing:

I. 20 protons and 20 neutrons.

II. 21 protons and 19 neutrons.

III. 22 neutrons and 18 protons.

IV. 20 protons and 22 neutrons.

V. 21 protons and 20 neutrons.

A) I, II, III

B) III, IV

C) I, V

D) I, IV and II, V

E) No isotopes are indicated.

27. By knowing the number of protons a neutral atom has, you should be able to determine

A) the number of neutrons in the neutral atom.

B) the number of electrons in the neutral atom.

C) the name of the atom.

D) two of the above.

E) none of the above

28. The number of neutrons in an atom is the same for all neutral atoms of that element.

A) True

B) False

29. The average mass of a carbon atom is 12.011. Assuming you were able to pick up only one carbon unit, the chances that you would randomly get one with a mass of 12.011 is

A) 0%.

B) 0.011%.

C) about 12%.

D) 12.011%.

E) greater than 50%.

30. The number of electrons in an atom is the same for all neutral atoms of that element.

A) True

B) False

31. An ion is formed

A) by either adding or subtracting protons from the atom.

B) by either adding or subtracting electrons from the atom

C) by either adding or subtracting neutrons from the atom.

D) All of the above are true.

E) Two of the above are true

32. Which of the following statements are true of uranium-238?

I. Its chemical properties will be exactly like those of uranium-235.

II. Its mass will be slightly different from that of an atom of uranium-235.

III. It will contain a different number of protons that an atom of uranium-235.

IV. It is more plentiful in nature than uranium-235.

A) III, IV

B) I, II, III

C) I, II, IV

D) II, III, IV

E) all of these

33. An isotope, X, of a particular element has an atomic number of 7 and a mass number of 15. Therefore,

A) X is an isotope of nitrogen

B) X has 8 neutrons per atom

C) X has an atomic mass of 14.0067

D) a and b

E) a, b, and c

34. Write the symbol for each of the following elements.

a) silver _____________

b) calcium _____________

c) iodine _____________

d) copper _____________

e) phosphorus _____________

35. How many oxygen atoms are there in one formula unit of Ca₃(PO₄)₂?

A) 2

B) 4

C) 6

D) 8

E) none of these

36. The formula of water, H₂O, suggests

A) there is twice as much mass of hydrogen as oxygen in each molecule.

B) there are two hydrogen atoms and one oxygen atom per water molecule.

C) there is twice as much mass of oxygen as hydrogen in each molecule.

D) there are two oxygen atoms and one hydrogen atom per water molecule.

E) none of these

37. Which of the following are incorrectly paired?

A) K, alkali metal

B) Ba, alkaline earth metal

C) O, halogen

D) Ne, noble gas

E) Ni, transition metal

38. Which of the following are incorrectly paired?

A) Phosphorus, Pr

B) Palladium, Pd

C) Platinum, Pt

D) Lead, Pb

E) Potassium, K

39. Which of the following are incorrectly paired?

A) Copper, Cu

B) Carbon, C

C) Cobalt, Co

D) Calcium, Ca

E) Cesium, Ce

40. All of the following are characteristics of metals except:

A) good conductors of heat

B) malleable

C) ductile

D) often lustrous

E) tend to gain electrons in chemical reactions

41. All of the following are characteristics of nonmetals except:

A) poor conductors of electricity

B) often bond to each other by forming covalent bonds

C) tend to form negative ions in chemical reactions with metals

D) appear in the upper left-hand corner of the periodic table

E) do not have a shiny (lustrous) appearance

42. What are the forms of elemental carbon?

A) graphite and diamond

B) graphite, diamond, and buckminsterfullerene

C) graphite and buckminsterfullerene

D) diamond and buckminsterfullerene

E) diamond, graphite, and carbonite

43. Which metals form cations with varying positive charges?

A) transition metals

B) Group 1 metals

C) Group 2 metals

D) Group 3 metals

E) metalloids

44. A species with 12 protons and 10 electrons is

A) Ne²⁺

B) Ti²⁺

C) Mg²⁺

D) Mg

E) Ne^2–

45. The correct name for LiCl is

A) lithium monochloride

B) lithium (I) chloride

C) monolithium chloride

D) lithium chloride

E) monolithium monochloride

46. The correct name for FeO is

A) iron oxide

B) iron (II) oxide

C) iron (III) oxide

D) iron monoxide

E) iron (I) oxide

47. The correct name for Ca²⁺ is

A) calcium

B) calcium (II) ion

C) calcium ion

D) calcium (I) ion

E) monocalcium ion

48. The formula for calcium bisulfate is

A) Ca(SO₄)₂

B) CaS₂

C) Ca(HSO₄)₂

D) Ca₂HSO₄

E) Ca₂S

49. Which of the following is incorrectly named?

A) Pb(NO₃)₂, lead(II) nitrate

B) NH₄ClO₄, ammonium perchlorate

C) PO₄^3–, phosphate ion

D) Mg(OH)₂, magnesium hydroxide

E) NO^3–, nitrite ion

50. All of the following are in aqueous solution. Which is incorrectly named?

A) H₂SO₄, sulfuric acid

B) H₃PO₄, phosphoric acid

C) H₃PO₄, phosphoric acid

D) HCN, cyanic acid

E) HCl, hydrochloric acid

51. All of the following are in aqueous solution. Which is incorrectly named?

A) HC₂H₃O₂, acetic acid

B) HBr, bromic acid

C) H₂SO₃, sulfurous acid

D) HNO₂, nitrous acid

E) HClO₃, chloric acid

52. Which of the following pairs is incorrect?

A) NH₄Br, ammonium bromide

B) K₂CO₃, potassium carbonate

C) BaPO₄, barium phosphate

D) CuCl, copper(I) chloride

E) MnO₂, manganese (IV) oxide

53. Write the names of the following compounds:

a) FeSO_{4 ________________}

b) NaC₂H₃O_{2 ________________}

c) KNO_{2 ________________}

d) Ca(OH)_{2 ________________}

e) NiCO_{3 ________________}

54. Write the chemical formulas for the following compounds or ions.

a) nitrate ion _________

b) aluminum oxide _________

c) ammonium ion _________

d) perchloric acid _________

e) copper(II) bromide _________

55. How many atoms (total) are there in one formula unit of Ca₃(PO₄)₂?

56. Three samples of a solid substance composed of elements A and Z were prepared. The first contained 4.31 g A and 7.69 g Z. The second sample was 35.9% A and 64.1% Z. It was observed that 0.718 g A reacted with Z to form 2.00 g of the third sample. Show that these data illustrate the law of definite composition.

57. Explain how Dalton’s atomic theory accounts for:

a) the law of conservation of mass.

b) the law of definite composition.

c) the law of multiple proportion.

58. Complete the following table.

Symbol	# protons	# neutrons	# electrons	Net Charge
Pb
	31	38		3+
	52	75	54
Mn		29		2+

59. Complete the following table.

Symbol ⁶⁹Ga⁺³

Number of protons 34

Number of neutrons 46

Number of electrons

Atomic number

Mass number

Net charge 0

60. Arsenopyrite is a mineral containing As, Fe, and S. Classify each element as metal, nonmetal, or metalloid.

Use the following to answer questions 61-70:

Name the following compounds:

61. Al₂(SO₄)₃

62. NH₄NO₃

63. NaH

64. K₂Cr₂O₇

65. CCl₄

66. AgCl

67. CaSO₄

68. HNO₃

69. N₂O₃

70. SnI₂

Use the following to answer questions 71-80:

Write the formula for:

71. sodium dichromate

72. iron (III) oxide

73. dinitrogen trioxide

74. cobalt (II) chloride

75. aluminum hydroxide

76. hydrosulfuric acid

77. sulfurous acid

78. nitric acid

79. phosphoric acid

80. acetic acid

81. A sample of chemical X is found to contain 5.0 grams of oxygen, 10.0 grams of carbon, and 20.0 grams of nitrogen. The law of definite proportion would predict that a 69 gram sample of chemical X should contain how many grams of carbon?

A) 5.0 grams

B) 6.9 grams

C) 10. grams

D) 15 grams

E) 20 grams

82. Consider the following two compounds: H₂O _.According to the law of multiple proportions, the ratio of hydrogen atoms per gram of oxygen in H₂O to hydrogen atoms per gram of oxygen in H₂O₂ is:

A) 1:1

B) 2:1

C) 1:2

D) 2:2

E) 4:1

83. You are given a compound with the formula MCl₂, in which M is a metal. You are told that the metal ion has 26 electrons. What is the identity of the metal?

A) Co

B) Al

C) Fe

D) Cr

E) Ni

84. Which of the following names is incorrect?

A) cobalt(II) chloride

B) magnesium oxide

C) aluminum(III) oxide

D) diphosphorus pentoxide

E) All of the above names are correct.

85. Which of the following statements is true?

A) Ions are formed by adding or removing protons or electrons.

B) Scientists believe that solids are mostly open space.

C) Heating water with a Bunsen burner results in a 2:1 mixture of hydrogen and oxygen gases.

D) At least two of the above statements (a-c) are true.

E) All of the statements (a-c) are false.

86. How many protons and electrons does the most stable ion for oxygen have?

# protons # electrons

A) 10 8

B) 8 6

C) 6 8

D) 8 8

E) 8 10

87. How many of the following postulates of Dalton's atomic theory are still scientifically accepted?

I. All atoms of the same element are identical.

II. Compounds are combinations of different atoms.

III. A chemical reaction changes the way atoms are grouped together.

IV. Atoms are indestructible.

A) 0

B) 1

C) 2

D) 3

E) 4

Answer Key

1. E

2. D

3. A

4. C

5. E

6. A

7. B

8. E

9. A

10. D

11. C

12. A

13. C

14. D

15. A

16. E

17. A

18. E

19. D

20. E

21. A

22. B

23. E

24. B

25. E

26. D

27. D

28. B

29. A

30. A

31. B

32. C

33. D

34. a) Ag, b) Ca, c) I, d) Ci, e) P

35. D

36. B

37. C

38. A

39. E

40. E

41. D

42. B

43. A

44. C

45. D

46. B

47. C

48. C

49. E

50. D

51. B

52. C

53. a) iron (II) sulfate

b) sodium acetate

c) potassium nitrite

d) calcium hydroxide

e) mickel (II) carbonate

54. a) NO3– b) Al2O3 c) NH4+ d) HClO4 e) CuBr2

55. 13

56. See Sec. 2.2 of Zumdahl, Chemistry.

57. See Sec. 2.3 of Zumdahl, Chemistry.

58.

Symbol # protons # neutrons # electrons Net Charge

Pb 82 124 82 0

Ga 31 38 28 3+

Te 52 75 54 2–

Mn 25 29 23 2+

59. Symbol 69Ga+3 80Se

Number of protons 31 34

Number of neutrons 38 46

Number of electrons 28 34

Atomic number 31 34

Mass number 69 80

Net charge +3 0

60. As = metalloid, Fe = metal, S = nonmetal

61. aluminum sulfate

62. ammonium nitrate

63. sodium hydride

64. potassium dichromate

65. carbon tetrachloride

66. silver chloride

67. calcium sulfate

68. nitric acid

69. dinitrogen trioxide

70. tin(II) iodide

71. Na₂Cr₂O₇

72. Fe₂O₃

73. N₂O₃

74. CoCl₂

75. Al(OH)₃

76. H₂S

77. H₂SO₃

78. HNO₃

79. H₃PO₄

80. CH₃COOH

81. E

82. B

83. E

84. C

85. B

86. E

87. C

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