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| 1 | |
Which is not a redox reaction? |
| | A) | 4 Al (s) + 3 O2(g) + 6 H2O (l) → 4 Al(OH)3(s) |
| | B) | 2 AgBr (s) + light → 2 Ag (s) + Br2(l) |
| | C) | Zn (s) + 2 MgO2(s) + H2O (l) → Zn(OH)2(s) + Mn2O3(s) |
| | D) | NaCl (s) → Na+ (aq) + Cl¯ (aq) |
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| 2 | |
This reaction represents __________ in an electrochemical cell.
Zn (s) + 2 MnO2(s) + H2O (l) → Zn(OH)2(s) + Mn2O3(s) |
| | A) | only the half-reaction of oxidation |
| | B) | only the half-reaction of reduction |
| | C) | the overall reaction |
| | D) | that cannot occur |
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| 3 | |
This type of alkaline cell is commonly used to power flashlights. Which is the anode of the cell?
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| | A) | carbon rod |
| | B) | paste of KOH, MnO2 |
| | C) | zinc can |
| | D) | water |
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| 4 | |
In which of these is energy created by a spontaneous chemical reaction and then converted into electrical energy? |
| | A) | a galvanic cell |
| | B) | an electrolytic cell |
| | C) | a solar cell |
| | D) | a hydroelectric cell |
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| 5 | |
Which is not a property of an ordinary dry-cell flashlight battery? |
| | A) | It has a characteristic electrical potential. |
| | B) | Two specific and different reactions occur: one at the anode and one at the cathode. |
| | C) | The voltage increases with the size of the battery. |
| | D) | It is non-rechargeable. |
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| 6 | |
What type of electrochemical device is used in the standard gasoline-powered automobile shown below?
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| | A) | photovoltaic cells |
| | B) | fusion-based reactors |
| | C) | methanol-based fuels |
| | D) | lead-acid storage batteries |
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| 7 | |
In a galvanic cell, |
| | A) | oxidation takes place at the cathode. |
| | B) | oxidation and reduction take place at the same time at different electrodes. |
| | C) | electrons travel through the cell from cathode to anode. |
| | D) | electrical energy is used to reverse the chemical reaction in the cell. |
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| 8 | |
Very small mercury "button" batteries have been used in many applications in the past. Why have they now been mostly replaced by other kinds of batteries? |
| | A) | Mercury has become far too expensive to use in batteries. |
| | B) | Mercury is poisonous and difficult to dispose of. |
| | C) | Mercury button batteries cannot produce enough current for many modern devices. |
| | D) | Although small mercury batteries can be made, they are too heavy to use in most applications. |
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| 9 | |
All batteries |
| | A) | contain both an anode and a cathode. |
| | B) | produce the same voltage. |
| | C) | produce the same amount of current. |
| | D) | can be recharged. |
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| 10 | |
What condition must be met for a battery to be rechargeable? |
| | A) | Either its anode or its cathode must generate a gas as a result of the electrochemical reaction. |
| | B) | It must generate electricity using an acid-base reaction rather than using an oxidation-reduction reaction. |
| | C) | The battery must be open to the outside so that internal pressure will not build up. |
| | D) | The electrochemical reaction of the battery must be reversible. |
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| 11 | |
The Toyota Prius, a hybrid car, uses |
| | A) | both a nickel-metal hydride battery and a conventional gasoline-powered engine. |
| | B) | two different types of electrochemical cells, or batteries. |
| | C) | a conventional gasoline-powered engine and an ethanol-powered engine. |
| | D) | an electrochemical cell and a hydrogen-oxygen fuel cell. |
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| 12 | |
What does this figure depict?
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| | A) | A fuel cell capable of converting chemical energy directly to electricity without combustion. |
| | B) | An energy-saving device for separating hydrogen from water. |
| | C) | A rechargeable alkaline cell that can be grouped with other cells and used to power space flight. |
| | D) | An electrochemical cell to carry out the combustion of methane with oxygen. |
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| 13 | |
This reaction takes place in a hydrogen-oxygen fuel cell.
2 H2(g) + O2(g) → 2 H2O(l)
What occurs at the anode? |
| | A) | the oxidation of O2 |
| | B) | the oxidation of H2 |
| | C) | the reduction of O2 |
| | D) | the reduction of H2 |
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| 14 | |
The electrolyte in PEM fuel cells |
| | A) | allows electrons to flow but blocks the flow of H+ ions. |
| | B) | allows H+ ions to flow but blocks the flow of electrons. |
| | C) | allows both electrons and H+ ions to flow. |
| | D) | blocks the flow of both electrons and H+ ions. |
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| 15 | |
Why do we burn natural gas and gasoline as fuels but not H2? |
| | A) | Burning H2 produces significantly more pollutants than burning natural gas or gasoline. |
| | B) | H2 has about the lowest heat of combustion of any potential fuel, much lower than that of natural gas or gasoline. |
| | C) | Although hydrogen is abundant, pure H2 is not found naturally on Earth. It is expensive and difficult to separate from its common compounds. |
| | D) | There are no known methods for storing and transporting H2 safely. |
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| 16 | |
Which are advantages to replacing internal combustion engines with hydrogen fuel cells?
I. More energy efficient
II. No moving parts
III. H2 is more plentiful than petroleum
IV. Less harmful exhaust gasses
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| | A) | I and II only |
| | B) | I, II, and IV only |
| | C) | II, III and IV only |
| | D) | I, II, III, and IV |
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| 17 | |
What type of semiconductor is shown in this diagram?
Note: The smaller filled circles represent electrons. The larger filled circles represent silicon atoms. The checked circle represents a doping atom.
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| | A) | an arsenic-doped p-type silicon semiconductor |
| | B) | an arsenic-doped n-type silicon semiconductor |
| | C) | a gallium-doped p-type silicon semiconductor |
| | D) | a gallium-doped n-type silicon semiconductor |
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| 18 | |
Why is silicon the principal element used in solar cells? |
| | A) | Si is abundant. It is found in 25% of the Earth's crust. |
| | B) | Si acts as a semiconductor when hit by a photon of infrared or visible light. |
| | C) | Si is in the same family with C and has four outer electrons. |
| | D) | Si exists as separate, non-bonded atoms, making electron transfer relatively easy. |
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| 19 | |
A photovoltaic cell |
| | A) | contains only an n-type semiconductor. |
| | B) | uses a chemical fuel to generate electricity |
| | C) | converts light from the sun directly into electricity. |
| | D) | is a device meant to store electricity; its use is growing rapidly. |
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| 20 | |
Arrays of photovoltaic cells are |
| | A) | used in many countries, including the U.S., to produce electricity. |
| | B) | essential for space applications, but cannot be used on the surface of the earth. |
| | C) | an idea only for the future because of the cost involved in producing the cells. |
| | D) | an old technology that has proven to be impractical. |
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