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Physical Science Final Review Answers ____ 1. Ninety-nine percent of all the matter that can be observed in the universe exists as plasmas. ____ 2. Hydrochloric acid, HCl, is added to solid NaOH. After the reaction is complete, NaCl dissolved in water remains. What are the products of this chemical reaction? NaCl and H2O ____ 3. In an electron dot diagram, the symbol for an element is used to represent the nucleus and all non-valence electrons ____ 4. Which statement is true about the metalloid silicon? Silicon is a better conductor of electric current than sulfur is. ____ 5. In which of the substances in Figure 3-1 are the forces of attraction among the particles so weak that they can be ignored under ordinary conditions? Substance C ____ 6. number ____ 7. To find the number of neutrons in an atom, you would subtract atomic number from mass Which of the following is a heterogeneous mixture? a jar of mixed nuts ____ 8. Boyle’s law states that the volume of a gas is inversely proportional to its pressure if the temperature and number of particles are constant ____ 9. How many grams of CO2 are in 2.1 mol of the compound? 92.4 g ____ 10. The heat of fusion for water is the amount of energy needed for water to melt. ____ 11. Raising the temperature of a gas will increase its pressure if the volume of the gas and the number of particles are constant ____ 12. What physical properties of nylon and leather make them good materials to use for shoelaces? durability and flexibility ____ 13. You see a structural formula in which the symbols for elements are connected by a long dash. You can assume that the chemical bonds in the compound are covalent. ____ 14. Democritus thought that matter was made of tiny particles that were all round and smooth ____ 15. Which of the following Group 1A elements is the most reactive? Fr ____ 16. How does increasing the amount of carbon in steel affect its properties? Carbon makes the lattice harder and stronger. ____ 17. The phase change in which a substance changes from a solid to a liquid is melting. ____ 18. Which statement about metals is true? Electrons in a metal lattice are free to move ____ 19. Figure 5-1 shows a portion of a blank periodic table. Identify the segments labeled A and B A is a period and B is a group. ____ 20. The standard on which the atomic mass unit is based is the mass of a carbon-12 atom ____ 21. The water molecule H2O is polar because it contains two polar single bonds and its molecule has a bent shape ____ 22. Which of the following Group 7A elements is the most reactive? F (fluorine) ____ 23. What is the difference between an atom in the ground state and an atom in an excited state? The atom in an excited state has more energy and is less stable than the atom in the ground state. ____ 24. The unit for atomic mass is amu ____ 25. Metallic bonding is similar to ionic bonding because there is an attraction between positively charged and negatively charged particles. ____ 26. A substance that is made up of only one kind of atom is a(an) element. ____ 27. To keep them from reacting, some highly reactive elements are stored in argon. ____ 28. For the chemical reaction C2H6 + 137 kJ C2H4 + H2, the chemical energy of the products is greater than the chemical energy of the reactant ____ 29. Which halogen is most likely to react? F (fluorine) ____ 30. The name iron(II) indicates that a compound contains iron ions with a 2+ charge. ____ 31. same charge Which statement about subatomic particles is NOT true? Protons and neutrons have the ____ 32. The phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first is sublimation. ____ 33. Group 7A of the periodic table contains the most reactive nonmetals ____ 34. What is the result of a force distributed over an area? pressure ____ 35. If a solid piece of naphthalene is heated and remains at 80°C until it is completely melted, you know that 80ºC is the freezing point of naphthalene. melting point of naphthalene. ____ 36. When magnesium carbonate, MgCO2, reacts with nitric acid, HNO3, magnesium nitrate and carbonic acid form. Carbonic acid then breaks down into water and carbon dioxide. Which two types of reactions take place in this process? double-replacement and decomposition Figure 7-1 ____ 37. The reaction in Figure 7-1 shows the formation of ammonia from nitrogen and hydrogen in the Haber process. What will be the effect on the equilibrium if the temperature is increased and some of the ammonia is removed from the system? Any effect will depend on the amount of change of temperature and concentration. ____ 38. Which of the following is a typical property of an ionic compound? tendency to shatter when struck ____ 39. As you move from left to right across a period, the number of valence electrons increases. ____ 40. ____ 41. freezing Which element is found in nature only in compounds? sodium During which phase change does the arrangement of water molecules become more orderly? ____ 42. Which of the following is a clue of a chemical change? a gas forms when vinegar and baking soda are mixed ____ 43. Moving from left to right across a row of the periodic table, which of the following values increases by exactly one from element to element? atomic number ____ 44. A substance has a melting point of 0ºC and a boiling point of 100ºC. The substance is most likely water ____ 45. Which of the following does NOT show the law of conservation of mass? 24 mL of Mg burn in 32 mL O2 to produce 56 mL of MgO ____ 46. Atoms of the most reactive elements tend to have one or seven valence electrons ____ 47. Which of the following are pure substances? compounds ____ 48. Fluorine, F, forms a binary ionic compound with lithium, Li. What is the name of this compound? lithium fluoride ____ 49. The tendency of an element to react is closely related to the number of valence electrons in atoms of the element. ____ 50. an atom In an atomic model that includes a nucleus, positive charge is concentrated in the center of ____ 51. Which phrase best describes a metallic bond? the attraction between a metal cation and a shared pool of electrons ____ 52. The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided? atom ____ 53. In the compound MgCl2, the subscript 2 indicates that there are two chloride ions for each magnesium ion ____ 54. Which statement about subatomic particles is true? An electron has far less mass than either a proton or neutron ____ 55. is a gas. If you move a substance from one container to another and its volume changes, the substance ____ 56. Which of the following statements is true about what happens during a chemical reaction? Bonds of the reactants are broken, and bonds of the products are formed ____ 57. Which element is found in most of the compounds in your body except for water? carbon ____ 58. What is the symbol for aluminum? Al ____ 59. An industrial process makes calcium oxide by decomposing calcium carbonate. Which of the following is NOT needed to calculate the mass of calcium oxide that can be produced from 4.7 kg of calcium carbonate? the balanced chemical equation ____ 60. A mixture that appears to contain only one substance is a(an) homogeneous mixture ____ 61. Which of the following compounds does NOT contain molecules? NaCl ____ 62. Which of the following formulas represents a compound whose molecules contain a triple bond? NN____ 63. Which of the following has the highest viscosity? corn syrup ____ 64. Which of the following will cause a decrease in gas pressure in a closed container? lowering the temperature ____ 65. conserves Which of the following does NOT state what the arrow means in a chemical equation? ____ Which statement is true about oxygen-17 and oxygen-18? They are isotopes of oxygen 66. ____ 67. Which of the following groups contain three elements with stable electron configurations? helium, xenon, neon ____ 68. Alkali metals, alkaline earth metals, and aluminum all form ions with positive charges equal to the group number. ____ 69. The coefficients in a balanced chemical equation always can express the ratio of moles of reactants and products ____ 70. A gas has no definite shape or definite volume ____ 71. One twelfth the mass of a carbon-12 atom is used to define a(an) atomic mass unit. ____ 72. Many metals can be drawn into thin wires without breaking because cations are still surrounded by electrons when they shift their positions in the lattice ____ 73. Ionization energies tend to increase from left to right across a period ____ 74. The reaction H2CO3 + H2O H3O+ + HCO3– takes place in water. What happens to the equilibrium when the pressure is increased? It does not change ____ 75. Mendeleev gave the name eka-aluminum to a(an) unknown element he predicted would have properties similar to those of aluminum Figure 6-1 ____ 76. Study the electron dot diagrams for lithium, carbon, fluorine, and neon in Figure 6-1. Choose the statement that correctly identifies the most stable of the elements. Neon is the most stable element because its highest occupied energy level is filled. ____ 77. The formation of an ionic bond involves the transfer of electrons. ____ 78. Compared with Group 2A elements, Group 6A elements have more valence electrons ____ 79. Two highly reactive elements in Period 2 are the metal lithium and the nonmetal fluorine ____ lost 80. Which of the following takes place during a redox reaction? Electrons are both gained and ____ 81. Which of the following is a balanced chemical equation for the synthesis of NaBr from Na and Br2? 2Na + Br2 2NaBr ____ 82. During a phase change, the temperature of a substance does not change. ____ 83. Which of the following provides the best analogy for an electron in an atomic orbital? a bee trying to escape from a closed jar ____ 84. Flammability is a material’s ability to burn in the presence of oxygen. ____ 85. In general, if the temperature of a chemical reaction is increased, the reaction rate increases. ____ 86. Reaction rates do NOT tell you how fast substances are changing state. ____ 87. Which statement about electrons and atomic orbitals is NOT true? An electron has the same amount of energy in all orbitals. ____ 88. Which list of elements contains only metals? tin, copper, cesium ____ 89. Which of the following is NOT part of John Dalton’s atomic theory? Atoms contain subatomic particles. ____ 90. When a physical change in a sample occurs, which of the following does NOT change? Composition ____ 91. What type of change occurs when water changes from a solid to a liquid? a phase change a physical change ____ 92. reactant Which of the following is NOT always true about a synthesis reaction? There is only one ____ 93. Methane, CH4, burns in oxygen gas to form water and carbon dioxide. What is the correct balanced chemical equation for this reaction? CH4 + 2O2 2H2O + CO2 ____ 94. Suppose an atom has a mass number of 23. Which statement is true beyond any doubt? The number of protons in the nucleus does not equal the number of neutrons ____ 95. Forces of attraction limit the motion of particles most in a solid. ____ 96. Which of the following is a physical change? sawing a piece of wood in half ____ 97. Water has a higher boiling point than expected because of the strong attractions between polar water molecules ____ 98. In a periodic table, a set of properties repeats from row to row. ____ 99. Matter that has a definite volume but no definite shape is a liquid. ____ 100. You are about to open a container of soy milk but notice that there are instructions to “shake well before serving.” The soy milk is most likely a solution. Essay 101. Suppose you want to separate the leaves, acorns, and twigs from a pile of soil. Filtration and distillation are two processes of separating mixtures. Explain which process you would use and why. 102. Fluorine is the most reactive nonmetal. To fluorine’s immediate right in the periodic table is neon, a noble gas that does not form chemical bonds. Explain this contrast in reactivity in terms of atomic structure. 103. Explain why rust forms in steel tanks that hold seawater in ships. How can nitrogen be used to reduce rust in these tanks? 104. In science lab, your teacher gives you two small pieces of matter and tells you that one piece is a metal and one is a nonmetal. Without changing the size or shape of the pieces, how could you test them to determine which is the metal? 105. A sample of calcium contains calcium-40, calcium-44, calcium-42, calcium-48, calcium-43, and calcium-46 atoms. Explain why these atoms can have different mass numbers but must have the same atomic number. 106. Describe how water can change from a liquid to a vapor at temperatures lower than its boiling point. 107. Why were the elements gallium (Ga), scandium (Sc), and germanium (Ge) important to Mendeleev? ESSAY 101. ANS: Filtration would be used because it is the process of separating mixtures based on the size of their particles (or pieces). A screen could be used to separate the mixture. The holes in the screen would need to be large enough to allow the soil to pass through but not the leaves, acorn, or twigs. PTS: 1 DIF: L2 OBJ: 2.2.4 102. ANS: The electron configuration of an element determines its reactivity. Fluorine, with seven valence electrons, tends to gain one electron to fill its highest occupied energy level. Neon, with eight valence electrons, has a stable electron configuration. Neon’s highest occupied energy level holds the maximum possible number of electrons. PTS: 1 DIF: L2 OBJ: 6.1.1 STA: 1.1.9-11.H.a 103. ANS: Rust forms in the tanks because oxygen dissolved in the water reacts with iron in the steel. Nitrogen gas can be pumped into the tanks. The nitrogen displaces some of the dissolved oxygen. Because nitrogen is less reactive than oxygen, less rust forms. PTS: 1 DIF: L2 OBJ: 2.3.1 STA: 1.1.9-11.A.b | 1.1.9-11.G.a | 1.1.9-11.G 104. ANS: You could see which piece conducts an electric current or which piece is a better conductor of heat. PTS: 1 DIF: L2 OBJ: 5.2.3 STA: 1.1.9-11.A.d | 1.1.9-11.F.b 105. ANS: All the atoms of an element have the same atomic number because the atomic number equals the number of protons in an atom. If one of the atoms had a different number of protons, the atom would not be a calcium atom. The mass number can vary because it is the sum of the protons and neutrons, and isotopes of an element can have different numbers of neutrons. PTS: 1 DIF: L2 OBJ: 4.2.2 STA: 1.1.9-11.E.c | 1.1.9-11.E.b 106. ANS: Water can evaporate at temperatures lower than its boiling point. Evaporation can take place at the surface of water because some water molecules are moving fast enough to escape the liquid and vaporize. The higher the temperature is, the faster the water molecules move, on average, and the faster evaporation takes place. PTS: 1 DIF: L2 OBJ: 3.3.4 STA: 1.1.9-11.D.a | 1.1.9-11.D.b | 1.1.9-11.D 107. ANS: Mendeleev predicted the properties of these undiscovered elements from data in his periodic table. When the elements were discovered, their actual properties were found to be a close match to those Mendeleev had predicted. Their discovery provided evidence of the usefulness of Mendeleev’s periodic table. PTS: 1 DIF: L1 OBJ: 5.1.2