Choose the best answer.
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1 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The proportion of oxygen in air is about ________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | 1/5 |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | 1/3 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | 1/2 |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | 4/5 |
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2 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) A substance of unknown composition is heated in an open container. As a result, ______________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | its mass decreases |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | its mass remains the same |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | its mass increases |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | any of the above, depending on the nature of the substance and the temperature reached |
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3 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) When a piece of metal is oxidized, the resulting oxide is _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | lighter than the original metal |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | the same weight as the original metal |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | heavier than the original metal |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | any of the above, depending on the metal |
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4 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Chemical energy is stored within atoms, molecules, and ions as _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | activation energy |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | electron kinetic energy |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | electron potential energy |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | thermal energy |
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5 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) A chemical reaction that absorbs energy is called _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | endothermic |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | exothermic |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | activated |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | oxidation-reduction |
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6 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) If a given reaction is exothermic, the reverse reaction ___________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | is exothermic |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | is endothermic |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | may involve no energy change |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | any of the above, depending on the reaction |
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7 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Reactions that give off energy ________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | never require activation energy |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | sometimes require activation energy |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | always require activation energy |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | always require catalysts |
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8 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The neutralization of a strong acid by a strong base ____________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | absorbs energy |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | liberates energy |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | involves no energy change |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | requires a catalyst to occur |
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9 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The products of the complete combustion of hydrocarbon fuels are ________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | H2 and CO |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | H2 and CO2 |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | H2O and CO |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | H2O and CO2 |
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10 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Of the following substances, the one that gives off the most heat per gram when it is burned is _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | hydrogen |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | methane |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | gasoline |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | coal |
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11 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Acid rain never contain dissolved _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | carbon dioxide |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | nitric acid |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | sulfuric acid |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | acetic acid |
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12 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The least polluting of the following fuels is _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | coal |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | gasoline |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | diesel fuel |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | natural gas |
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13 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Reaction rates increase with temperature primarily because ___________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | dissociation into ions is more complete |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | more collisions occur between the molecules involved |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | more activated molecules are formed |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | equilibrium does not occur at high temperatures |
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14 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) At equilibrium, _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | both forward and reverse reactions have ceased |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | the forward and reverse reactions are proceeding at the same rate |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | the forward reaction has come to a stop, and the reverse reaction is just about to begin |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | the mass of reactants equals the mass of products |
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15 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The yield of the product C in the reversible reaction A + B + energy ↔ C can be increased by ______________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | decreasing the temperature |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | increasing the temperature |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | increasing the surface area of the reactants |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | changing the catalyst |
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16 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Reduction occurs when a substance __________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | loses electrons |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | gains electrons |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | combines with oxygen |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | reacts with an acid |
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17 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) A catalyst affects which one or more of the following? |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | The energy needed for a chemical reaction to occur |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | The energy a chemical reaction gives off |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | The speed of a chemical reaction |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | Whether a substance is oxidized or reduced in a chemical reaction |
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18 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) When an electric current is passed through molten sodium chloride, ____________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | sodium metal is deposited at the positive electrode |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | sodium ions are deposited at the positive electrode |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | chlorine gas is liberated at the positive electrode |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | chlorine ions are liberated at the positive electrode |
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19 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) The quantity actually stored in a "storage battery" is _________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | electric charge |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | electric current |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | voltage |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | energy |
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20 | ![](/olcweb/styles/shared/spacer.gif) | ![](/olcweb/styles/shared/spacer.gif) Batteries and fuel cells employ __________________. |
| ![](/olcweb/styles/shared/spacer.gif) | A)![](/olcweb/styles/shared/spacer.gif) | oxidation reactions only |
| ![](/olcweb/styles/shared/spacer.gif) | B)![](/olcweb/styles/shared/spacer.gif) | reduction reactions only |
| ![](/olcweb/styles/shared/spacer.gif) | C)![](/olcweb/styles/shared/spacer.gif) | both oxidation and reduction reactions |
| ![](/olcweb/styles/shared/spacer.gif) | D)![](/olcweb/styles/shared/spacer.gif) | acid-base neutralization reactions |
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