Chemistry 105 Practice Test: Answer Key

Chemistry 105 Practice Test: Answer Key

Chem 105 Practice Test 1 Note: There will not be this many questions on your test, I just wanted to give you as much practice as possible. Also, none of these exact questions will be on the test, just similar questions. Also, make sure you can do the homework, as I may have some questions similar to the homework questions. 1. Molecules can be described as a. a mixture of two or more pure substances. b. a mixture of two or more elements that has a specific ratio between components. c. two or more atoms chemically joined together. d. a heterogeneous mixture e. a homogeneous mixture Answer: C 2. Dalton’s Atomic Theory states . that all elements have several isotopes. b. that matter is composed of small indestructible particles. c. that the properties of matter are determined by the properties of atoms. d. that energy is neither created nor destroyed during a chemical reaction. e. that an atom is predominantly empty space. Answer: B 3. Which of the following represents a hypothesis? a. Sodium reacts with water to form sodium hydroxide and hydrogen gas. b. Nitrogen gas is a fairly inert substance. c. Nickel has a silvery sheen. d. When a substance combusts, it combines with air. e. When wood burns, heat is given off. Answer: D . Which is true of a Scientific Theory (circle all that apply) a. It is an interpretation for an observation b. It is a general explanation for the manifestation and behavior of all nature c. It can be validated or invalidated by experiment and observation d. It describes why things happen Answer: B, C, and D 5. Mass (circle all that apply) a. Is dependent on location (gravity) b. Is the amount of matter in a substance and remains the same regardless of location c. can be measured by using a scale or balance d. is measured in ml Answer: B and C 6. The states of matter are a. Solid and gas b. Liquid and gas . Gas, solid, and liquid d. Gas, air, and vapor Answer: C 7. A liquid (circle all that apply) a. Has a definite volume b. Has particles that are less orderly and can move about freely c. Has particles that are tightly packed d. Has no definite volume or shape e. Answer: A and B 8. Identify dry ice as a solid, liquid, or gas. a. solid b. liquid c. gas d. both solid and liquid Answer: A 9. When a gas is cooled (circle all that apply) a. Its molecules have fewer energetic collisions b. The motion of the gas particles decrease c. The motion of gas particles increase d. Nothing happens to the gas particles

Answer: A and B 10. Classify each of the following as a mixture or a pure substance: a. Carbon dioxide _____________________ b. Blood ______________________ c. Helium (He) ______________________ d. Sugar water _______________________ Answer: A-pure substance; B-mixture; C-pure substance; D-mixture 11. Choose the pure substance from the list below. a. sea water b. sugar c. air d. lemonade e. milk Answer: B 12. Choose the heterogeneous mixture from the list below. a. Gatorade b. chlorine gas c. black coffee d. chicken noodle soup e. carbon (graphite) Answer: D 3. Which of the following statements about crystalline and amorphous solids is TRUE? a. A crystalline solid is composed of atoms or molecules arranged with long-range repeating order. b. An example of a crystalline solid is glass. c. An example of an amorphous solid is table salt (NaCl). d. An amorphous solid is composed of atoms or molecules with a majority of its volume empty. e. All of the above statements are TRUE. Answer: A 14. A substance that can’t be chemically broken down into simpler substances is considered to be a. a homogeneous mixture. b. an element. c. a heterogeneous mixture. d. compound. e. an electron. Answer: B 15. Two or more substances in variable proportions, where the composition is constant throughout are considered a. a compound. b. an element. c. a heterogeneous mixture. d. a homogeneous mixture. e. a crystalline solid. Answer: D 16. Which of the following are examples of physical change? a. sugar is dissolved in water. b. coffee is brewed. c. dry ice sublimes. d. ice (solid water) melts. e. All of these are examples of physical change. Answer: E 17. Which of the following are examples of a chemical change? a. coffee brewing b. water boiling c. nails rusting d. alt dissolves in water e. None of the above are chemical changes. Answer: C 18. Which of the following represents a physical property? a. Sodium metal is extremely reactive with chlorine gas. b. Mercury is a silver liquid at room temperature. c. the tendency of aluminum to “rust” d. the flammability of butane fuel e. the unreactive nature of argon gas Answer: B 19. Define thermal energy. a. Energy associated with the temperature of an object. b. Energy associated with the motion of an object. c. Energy associated with the force of an object. d. Energy associated with the gravity of an object. e.

Energy associated with the position of an object. Answer: A 20. 33) Which of the following are examples of intensive properties? a. density b. volume c. mass d. None of the above are examples of intensive properties. e. All of the above are examples of intensive properties. Answer: A 21. If the temperature is 178°F, what is the temperature in degrees celsius? a. 352°C b. 451°C c. 67°C d. 81. 1°C e. 378°C Answer: D 22. If the temperature is 25°C, what is the temperature in °F? a. 45°F b. 298. 15°F c. 77°F d. -3. 89°F Answer: C 23. If the temperature is 25°C, what is the temperature in K? a. 45 K b. 298 K c. 77 K . -3. 89 K Answer: B 24. Determine the density of an object that has a mass of 149. 8 g and displaces 12 . 1 mL of water when placed in a graduated cylinder. a. 8. 08 g/mL b. 1. 38 g/mL c. 12 . 4 g/mL d. 18. 1 g/mL e. 11. 4 g/mL Answer: C 25. A student performs an experiment to determine the density of a sugar solution. She obtains the following results: 4. 11 g/mL, 4. 81 g/mL, 4. 95 g/mL, 3. 75 g/mL. If the actual value for the density of the sugar solution is 4. 75 g/mL, which statement below best describes her results? a. Her results are precise, but not accurate. b. Her results are accurate, but not precise. . Her results are both precise and accurate d. Her results are neither precise nor accurate. e. It isn’t possible to determine with the information given. Answer: D 26. Read the water level with the correct number of significant figures. a. 5 mL b. 5. 3 mL c. 5. 32 mL d. 5. 320 mL e. 5. 3200 mL Answer: B (Note: Remember, your last significant figure is the one that is uncertain. Because there are only whole number marks, the most certain significant figure is the 5, then we estimate where the meniscus of the liquid is between the 5 and the 6. This is why the correct reading is 5. 3, where the 3 is uncertain.

If there were marks between the whole numbers, the correct answer would have 3 significant figures, since you could more accurately determine the volume. ) 27. Read the length of the metal bar with the correct number of significant figures. a. 20 cm b. 15 cm c. 15. 0 cm d. 15. 00 cm e. 15. 000 cm Answer: D 28. How many significant figures are in: 1009. 630 mL? a. 1009. 630 ml _____7______ b. 3. 408 x 104 m _____4_______ c. 0. 0005890 g ______4_______ 29. Complete the following calculations and report your answer with the correct number of significant figures: a. (249. 362 + 41)/63. 498 = ____4. 57________ b. 433. 621 + 0. 02 = ____433. 4_________ c. (965. 43 x 3. 911) + 9413. 4136 = ____1. 319 x 104 or 13190_____ 30. What wavelength of light would you report in units of nm, if the light had a wavelength of 7. 60 x 10-10 m? a. 7. 60 ? 10-3 nm b. 7. 60 ? 10-19 nm c. 1. 32 nm d. 0. 760 nm e. 760 nm Answer: D 31. How many cm3 are contained in 3. 77 ? 104 mm3? a. 3. 77 ? 104 cm3 b. 3. 77 ? 101 cm3 c. 3. 77 ? 10-10 cm3 d. 3. 77 ? 1020 cm3 e. 3. 77 ? 106 cm3 f. Answer: B 32. If a room requires 25. 4 square yards of carpeting, what is the area of the floor in units of ft2? (3 ft = 1 yd) a. 76. 2 ft2 b. 8. 47 ft2 c. 282 ft2 d. 229 ft2 e. 68. 6 ft2 Answer: D 33. Convert 15. km to miles. (use conversions in the back of your book. These will be given for the test a. 24. 1 miles b. 9. 32 miles c. 591 miles d. 33. 1 miles e. Answer: B 34. Gas is sold for $1. 399 per liter in Toronto, Canada. Your car needs 12. 00 gallons. How much will your credit card be charged in dollars? ( use conversions in the back of your book. These will be given for the test) a. $16. 79 b. $67. 15 c. $4. 44 d. $63. 54 Answer: D 35. Crude oil is an example of a. a compound. b. an element. c. a heterogeneous mixture. d. a homogeneous mixture. Answer: C 36. NaCl is an example of a. a compound. b. an element. c. a heterogeneous mixture. . a homogeneous mixture. Answer: A 37. A piece of metal ore weighs 8. 25 g. When a student places it into a graduated cylinder containing water, the liquid level rises from 21. 25 mL to 26. 47 mL. What is the density of the ore? a. 0. 312 g/mL b. 0. 633 g/mL c. 1. 58 g/mL d. 3. 21 g/mL Answer: C 38. A mass of mercury occupies 0. 950 L. What volume would an equal mass of ethanol occupy? The density of mercury is and the density of ethanol is 0. 789 g/mL. a. 0. 0553 L b. 0. 0613 L c. 16. 3 L d. 18. 1 L Answer: C 39. Round the following number to four significant figures and express the result in standard exponential notation: 229. 13 a. 0. 2296 ? 103 b. 229. 6 c. 2. 296 ? 10-2 d. 2. 296 ? 102 e. 22. 96 ? 10-1 Answer: D 40. Round off 00907506 to four significant figures. a. 0091 b. 9076 c. 9100 d. 9. 075 ? 105 Answer: D 41. The diameter of an atom is approximately 1 ? 10-10 m. What is the diameter in millimeters? a. 1 ? 10-16 mm b. 1 ? 10-13 mm c. 1 ? 10-7 mm d. 1 ? 10-4 mm Answer: C 42. How many liters of wine can be held in a wine barrel whose capacity is 26. 0 gal? 1 gal = 4 qt = 3. 7854 L. a. 1. 46 ? 10-4 b. 0. 146 c. 98. 4 d. 6. 87 ? 103 e. 6. 87 Answer: C 43. 128) How many liters of air are in a room that measures 10. 0 x 11. 0 ft and has an 8. 0 ft ceiling? 1 in. = 2. 54 cm (exactly); 1 L = 103 cm3. a. 2. 49 ? 104 b. 92. 8 c. 26. 8 d. 2. 68 ? 107 e. 8. 84 ? 105 Answer: A 44. 1) Which of the following is an example of the law of multiple proportions? a. A sample of chlorine is found to contain three times as much Cl-35 as Cl-37. b. Two different compounds formed from carbon and oxygen have the following mass ratios: 1. 33 g O: 1 g C and 2. 66 g O: 1 g C. c. Two different samples of table salt are found to have the same ratio of sodium to chlorine. d. The atomic mass of bromine is found to be 79. 90 amu. e. Nitrogen dioxide always has a mass ratio of 2. 8 g O: 1 g N. Answer: B 45. Identify the element that has an atomic number of 40. a. neon b. calcium c. zirconium d. bromine Answer: C 46. The atomic mass for cadmium is a. 48 b. 112. 41 c. 40. 08 d. 20 Answer: B 47. The mass number is equal to a. the sum of the sum of the electrons and protons. b. the sum of the sum of the neutrons and electrons. c. the sum of the number of protons, neutrons, and electrons. d. the sum of the number of protons and neutrons. Answer: D 48. What element is defined by the following information? p+ = 11n° = 12 e- = 11 a. sodium b. vanadium c. magnesium d. titanium Answer: A 49. ) What does “X” represent in the following symbol? X a. silicon b. sulfur c. zinc d. ruthenium e. nickel Answer: A 50. 11) Determine the number of protons, neutrons and electrons in the following: X a. p+ = 18n° = 18e- = 22 b. p+ = 18n° = 22e- = 18 c. p+ = 22n° = 18e- = 18 d. p+ = 18n° = 22e- = 40 e. p+ = 40 n° = 22e- = 18 Answer: B 51. Identify a cation. a. An atom that has lost an electron. b. An atom that has gained an electron. c. An atom that has lost a proton. d. An atom that has gained a proton. Answer: A 52. What element is defined by the following information? p+ = 17n° = 20 e- = 17 a. calcium b. rubidium c. hlorine d. neon e. oxygen Answer: C 53. What species is represented by the following information? p+ = 17 n° = 18 e- = 18 a. Cl b. Cl- c. Ar d. Ar+ e. Kr f. Answer: B 54. Give the number of electrons for carbon-14, with a -2 charge . a. 7 b. 4 c. 6 d. 8 Answer: D 55. Predict the charge that an aluminum ion would have. a. 5- b. 1+ c. 1- d. 2+ e. 3+ Answer: E 56. Predict the charge that the ion formed from bromine would have. a. 1- b. 2+ c. 1+ d. 4+ e. 2- f. Answer: A 57. Which of the following elements is NOT a metal? a. Ba b. Mg c. Xe d. Pb e. Ga Answer: C 58. Which of the following elements is a noble gas? a. Ar b.

Br c. N d. O e. K Answer: A 59. Which of the following elements is an alkali metal? a. Zn b. Xe c. F d. Li e. Ca Answer: D 60. Which of the following statements is FALSE? a. Anions are usually larger than their corresponding atom. b. Metals tend to form cations c. Atoms are usually larger than their corresponding cation. d. The halogens tend to form 1+ ions. e. Nonmetals tend to gain electrons. Answer: D 61. Which of the following does NOT describe a nonmetal? a. Tend to gain electrons b. Found in the upper right hand corner of the periodic table. c. Poor conductor of electricity d. Nonmetals are generally unreactive. e.

Poor conductor of heat. Answer: D 62. Silver has an atomic mass of 107. 868 amu. The Ag-109 isotope (108. 905 amu) is 48. 16%. What is the amu of the other isotope? a. 106. 905 amu b. 106. 908 amu c. 106. 903 amu d. D) 106. 911 amu Answer: A 63. Which of the following contains the MOST atoms? You shouldn’t need to do a calculation here. a. 10. 0 g Ne b. 10. 0 g He c. 10. 0 g Ar d. 10. 0 g Kr e. 10. 0 g Mg Answer: B 64. How many silver atoms are contained in 3. 75 moles of silver? a. 6. 23 ? 1024 silver atoms b. 2. 26 ? 1024 silver atoms c. 1. 61 ? 1023 silver atoms d. 2. 44 ? 1026 silver atoms e. 6. 50 ? 1025 silver atoms Answer: B 5. How many moles of potassium are contained in 449 g of potassium? a. 11. 5 moles b. 17. 6 moles c. 69. 2 moles d. 23. 9 moles e. 41. 5 moles Answer: A 66. What mass, in kg, does 5. 84 moles of titanium (Ti) have? a. 0. 352 kg b. 0. 122 kg c. 0. 820 kg d. 0. 280 kg e. 0. 632 kg Answer: D 67. How many moles of Cs are contained in 595 kg of Cs? a. 2. 23 ? 102 moles Cs b. 4. 48 ? 103 moles Cs c. 7. 91 ? 104 moles Cs d. 1. 26 ? 103 moles Cs e. 5. 39 ? 102 moles Cs Answer: B 68. How many iron atoms are contained in 354 g of iron? a. 2. 62 ? 1025 Fe atoms b. 2. 13 ? 1026 Fe atoms c. 4. 69 ? 1024 Fe atoms d. 3. 82 ? 1024 Fe atoms . 9. 50 ? 1022 Fe atoms Answer: D 69. Calculate the mass, in kg, of 4. 87 x 1025 atoms of Zn. a. 5. 29 kg b. 1. 89 kg c. 8. 09 kg d. 1. 24 kg e. 1. 09 kg Answer: A Match the following. A) Fe B) C C) Mg D) Si E) K 70. magnesium 71. carbon 72. potassium 73. iron 74. silicon Answers: 70) C 71) B 72) E 73) A 74) D 75. Give the name of the element whose symbol is Na. Answer: sodium 76. An atom of 131Xe contains ________ electrons. a. 131 b. 185 c. 77 d. 123 e. 54 Answer: E 77. An ion has 8 protons, 9 neutrons, and 10 electrons. The symbol for the ion is ________. a. 17O2- b. 17O2+ c. 19F+ d. 19F- e. 17Ne2+ Answer: A 78.

How many protons does the Br- ion possess? a. 34 b. 36 c. 6 d. 8 e. 35 Answer: E 79. Predict the charge of the most stable ion of potassium. a. 3+ b. 1- c. 2+ d. 2- e. 1+ Answer: E 80. What is the chemical symbol for mercury? a. Ag b. Au c. Hg d. Pb Answer: C 81. Which are isotopes? An atom that has an atomic number of 20 and a mass number of 42 is an isotope of an atom that has a. an atomic number of 21 and a mass number of 42. b. an atomic number of 20 and a mass number of 40. c. 22 neutrons and 20 protons. d. 22 protons and 20 neutrons. Answer: B 82. How many protons (p) and neutrons (n) are in an atom of Sr? a. 38 p, 52 n . 38 p, 90 n c. 52 p, 38 n d. 90 p, 38 n Answer: A 83. The mass number of an atom of 128Xe is ________. a. 54 b. 182 c. 74 d. 128 e. 120 Answer: D 84. What is the identity of element Q if the ion Q2+ contains 10 electrons? a. C b. O c. Ne d. Mg Answer: D 85. In which of the following sets do all species have the same number of electrons? a. F-, Ne, Mg2+ b. Ge, Se2-, Br- c. K+, Rb+, Cs+ d. Br, Br-, Br+ Answer: A 86. Argon belongs to the ________ group of the periodic table. a. alkali metal b. alkaline earth metal c. halogen d. noble gas Answer: D 87. Which of the following elements has chemical properties similar to tellurium? . fluorine b. hydrogen c. nitrogen d. sulfur Answer: D 88. An ionic bond is best described as: a. the sharing of electrons. b. the transfer of electrons from one atom to another. c. the attraction that holds the atoms together in a polyatomic ion. d. the attraction between 2 nonmetal atoms. e. the attraction between 2 metal atoms. Answer: B 89. What is the empirical formula for C4H10O2? a. C2H5O b. CHO c. C2H4O d. CHO2 e. CH2O Answer: A 90. Write a possible molecular formula for C4H4O. a. C8H8O2 b. C12H12O2 c. C2H2O d. C8H8O Answer: A 91. Which of the following is an atomic element? a. Br b. H c. N d. O e. Mg Answer: E 92.

Which of the following is a molecular element? a. Kr b. Ag c. S d. Mg e. Ti Answer: C 93. Which of the following is a molecular compound? a. CuCl2 b. KCl c. NaNO3 d. CH3Cl e. RbBr f. Answer: D 94. Which of the following is an ionic compound? a. SCl2 b. Mg3(PO4)2 c. Cl2O d. CH2O e. PF5 Answer: B 95. Write the formula for the compound formed between potassium and sulfur. a. KS b. KS2 c. K2S d. K2SO3 e. K3S2 Answer: C 96. Give the name for SnO. a. tin (I) oxide b. tin (II) oxide c. tin (III) oxide d. tin (IV) oxide Answer: B 97. Write the formula for strontium nitride. a. Sr3N2 b. Sr(NO3)2 c. SrN d. Sr2N3 e. Sr(NO2)2 Answer: A 98.

Write the name for Sn(SO4)2. Remember that Sn forms several ions. a. tin (I) sulfite b. tin (IV) sulfate c. tin sulfide d. tin (II) sulfite e. tin (I) sulfate Answer: B 99. Determine the name for CoCl2•6H2O. Remember that Co forms several ions. a. cobalt chloride hydrate b. cobalt (I) chloride heptahydrate c. cobalt (II) chloride heptahydrate d. cobalt (II) chloride hexahydrate e. cobalt (I) chloride Answer: D 100. Write the formula for copper (II) sulfate pentahydrate. a. Cu2SO3•H5 b. Cu2S•H2O c. CuS•5H2O d. (CuSO4)5 e. CuSO4•5H2O Answer: E 101. Determine the name for H2CO3. a. carbonous acid b. dihydrogen carbonate c. carbonic acid . hydrocarbonic acid e. hydrocarbide acid Answer: C 102. Identify the formula for nitric acid. a. HNO3 b. HNO2 c. HNO d. HNO4 Answer: A 103. Determine the name for P4O10. a. phosphorus (IV) oxide b. diphosphorus pentoxide c. phosphorus oxide d. phosphorus (II) oxide e. tetraphosphorus decoxide Answer: E 104. Calculate the molar mass for Mg(ClO4)2. a. 223. 21 g/mol b. 123. 76 g/mol c. 119. 52 g/mol d. 247. 52 g/mol e. 75. 76 g/mol Answer: A 105. Calculate the molar mass of Al(C2H3O2)3. a. 86. 03 g/mol b. 204. 13 g/mol c. 56. 00 g/mol d. 258. 09 g/mol e. 139. 99 g/mol Answer: B 106. How many millimoles of Ca(NO3)2 contain 4. 8 ? 1022 formula units of Ca(NO3)2? The molar mass of Ca(NO3)2 is 164. 10 g/mol. a. 12. 6 mmol Ca(NO3)2 b. 13. 0 mmol Ca(NO3)2 c. 20. 7 mmol Ca(NO3)2 d. 79. 4 mmol Ca(NO3)2 e. 57. 0 mmol Ca(NO3)2 Answer: D 107. How many C2H4 molecules are contained in 45. 8 mg of C2H4? The molar mass of C2H4 is 28. 05 g/mol. a. 9. 83 ? 1020 C2H4 molecules b. 7. 74 ? 1026 C2H4 molecules c. 2. 71 ? 1020 C2H4 molecules d. 3. 69 ? 1023 C2H4 molecules e. 4. 69 ? 1023 C2H4 molecules Answer: A 108. What is the mass of 9. 44 ? 1024 molecules of NO2? The molar mass of NO2 is 46. 01 g/mol. a. 205 g b. 294 g c. 721 g d. 341 g e. 685 g Answer: C 109.

Calculate the mass percent composition of sulfur in Al2(SO4)3. a. 28. 12 % b. 9. 372 % c. 42. 73 % d. 21. 38 % e. 35. 97 % Answer: A 110. How many moles of N2O3 contain 2. 55 ? 1024 oxygen atoms? (change the molecule) a. 1. 41 moles N2O3 b. 4. 23 moles N2O3 c. 12. 7 moles N2O3 d. 7. 87 moles N2O3 e. 2. 82 moles N2O3 Answer: A 111. How many moles of PCl3 contain 3. 68 ? 1025 chlorine atoms? a. 61. 1 moles PCl3 b. 20. 4 moles PCl3 c. 16. 4 moles PCl3 d. 54. 5 moles PCl3 e. 49. 1 moles PCl3 Answer: B 112. How many sodium ions are contained in 99. 6 mg of Na2SO3? The molar mass of Na2SO3 is 126. 05 g/mol. a. 1. 52 ? 1027 sodium ions . 4. 76 ? 1020 sodium ions c. 2. 10 ? 1021 sodium ions d. 1. 05 ? 1021 sodium ions e. 9. 52 ? 1020 sodium ions Answer: E 113. Determine the volume of hexane that contains 5. 33 ? 1022 molecules of hexane. The density of hexane is 0. 6548 g/mL and its molar mass is 86. 17 g/mol. a. 8. 59 mL b. 13. 5 mL c. 7. 40 mL d. 12. 4 mL e. 11. 6 mL Answer: E 114. Determine the molecular formula of a compound that has a molar mass of 92. 0 g/mol and an empirical formula of NO2. a. N2O3 b. N3O6 c. N2O4 d. NO2 e. N2O5 Answer: C 115. Determine the empirical formula for a compound that is 36. 86% N and 63. 14% O by mass. a. NO b. N2O c. NO2 d.

N2O3 e. NO3 Answer: D 116. Write a balanced equation to show the reaction of gaseous ethane with gaseous oxygen to form carbon monoxide gas and water vapor. a. 2 C2H6(g) + 7 O2(g) > 4 CO2(g) + 6 H2O(g) b. C2H6(g) + 5 O(g) > 2 CO(g) + 3 H2O(g) c. 2 C2H6(g) + 5 O2(g) > 4 CO(g) + 6 H2O(g) d. C2H6(g) + 7 O(g) > 2 CO2(g) + 3 H2O(g) e. 2 CH3(g) + 5 O(g) > 2 CO(g) + 3 H2O(g) Answer: C 117. Which of the following is one possible form of pentane? a. CH3CH2CH2CH2CH3 b. CH3CH=CHCH2CH3 c. CH3CH2CH2CH2CH2CH3 d. CH3CH2CH2CH2CH2NH2 e. CH3CH2-O-CH2CH2CH3 Answer: A 118. List the elements in a hydrocarbon Answer: hydrogen and carbon 119.

What type of bonding is found in the compound OF2? a. covalent bonding b. hydrogen bonding c. ionic bonding d. metallic bonding Answer: A 120. In which set do all elements tend to form cations in binary ionic compounds? a. K, Ga, O b. Sr, Ni, Hg c. N, P, Bi d. O, Br, I Answer: B 121. Rb2S is named a. rubidium disulfide. b. rubidium sulfide. c. rubidium(II) sulfide. d. rubidium sulfur. Answer: B 122. An aqueous solution of H2S is named a. hydrosulfuric acid. b. hydrosulfurous acid. c. sulfuric acid. d. sulfurous acid. Answer: A 123. What is the molar mass of nitrogen gas? a. 14. 0 g/mol b. 28. 0 g/mol c. 6. 02 ? 1023 g/mol d. 1. 20 ? 023 g/mol Answer: B 124. What mass of carbon dioxide, C O2, contains the same number of molecules as 3. 00 g of trichlorofluoromethane, CCl3F? a. 0. 106 g b. 0. 961 g c. 1. 04 g d. 9. 37 g e. Answer: B 125. Which of the following has the greatest mass? a. 3. 88 ? 1022 molecules of O2 b. 1. 00 g of O2 c. 0. 0312 mol of O2 d. All of the above have the same mass. Answer: A 126. A sample of pure calcium fluoride with a mass of 15. 0 g contains 7. 70 g of calcium. How much calcium is contained in 40. 0 g of calcium fluoride? a. 2. 27 g b. 7. 70 g c. 15. 0 g d. 20. 5 g Answer: D 127. What is the empirical formula of a compound that is 62. % C, 10. 4% H, and 27. 5% O by mass? a. C3HO b. C6HO3 c. C6H12O2 d. C5H10O2 e. C3H6O Answer: E 128. How many oxygen atoms are there in 7. 00 g of sodium dichromate, Na2Cr2O7? a. 0. 187 oxygen atoms b. 2. 30 ? 1021 oxygen atoms c. 1. 60 ? 1022 oxygen atoms d. 1. 13 ? 1023 oxygen atoms Answer: D 129. Methane and oxygen react to form carbon dioxide and water. What mass of water is formed if 0. 80 g of methane reacts with 3. 2 g of oxygen to produce 2. 2 g of carbon dioxide? a. 1. 8 g b. 2. 2 g c. 3. 7 g d. 4. 0 g Answer: A 130. Combustion analysis of 1. 200 g of an unknown compound containing carbon, hydrogen, and oxygen produced 2. 86 g of CO2 and 1. 134 g of H2O. What is the empirical formula of the compound? a. C2H5O b. C2H5O2 c. C2H10O3 d. C3H8O2 Answer: D 131. What is the stoichiometric coefficient for oxygen when the following equation is balanced using the lowest, whole-number coefficients? _____ C2H6O (l) + _____ O2(g) > _____ CO2(g) + _____ H2O(l) a. 9 b. 7 c. 5 d. 3 Answer: D 132. Calcium phosphate reacts with sulfuric acid to form calcium sulfate and phosphoric acid. What is the coefficient for sulfuric acid when the equation is balanced using the lowest, whole-numbered coefficients? a. 1 b. 2 c. 3 d. none of these Answer: C