Chemistry B Semester Exam
Use the periodic table and example bond table to answer the question.
Example Bond Energies of Ionic Compounds
Li–F = 1036 kJ/mol
Li-Br = 807 kJ/mol
Na-F= 923 kJ/mol
Na-Br = 747 kJ/mol
Given the general trend with bond energies, which of the compounds would have the smallest bond energy?
(1 point)
K-Br
Cs-F
Cs-Br
K-F
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Based on the differences in electronegativities, with which atom is francium (Fr) most likely to form an ionic bond? (1 point)
Fr–I = 1.96
Fr–At = 1.50
Fr–Se = 1.76
Fr–Cl = 2.46
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Which statement is the best description of the energy found in molecules of water? (1 point)
Colder molecules have more thermal energy.
A molecule's temperature is not connected to its energy.
Hotter molecules have more kinetic energy.
Colder molecules have more kinetic energy.
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When potassium permanganate and glycerol react, the potential energy of the products is less than the potential energy of the reactants. Which statement about this reaction is correct? (1 point)
The total potential energy of the system is constant.
The reaction is exothermic.
The activation energy of the system is negative.
The reaction is endothermic.
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Hydrochloric acid and sodium hydroxide react to produce water and sodium chloride in an endothermic reaction. Which statement must be true of the reaction? (1 point)
The bond energy used to break the bonds in hydrochloric acid and sodium hydroxide is less than the energy released to form the bonds in water and sodium chloride.
The energy of each bond in water and sodium chloride is greater than the energy of each bond in hydrochloric acid and sodium hydroxide.
More bond energy is absorbed on the reactants side than is released on the products side.
The total bond energy of water and sodium chloride is greater than the total bond energy of hydrochloric acid and sodium hydroxide.
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Imagine a graph. The x-axis is labeled "Time" and is measured in seconds, and the y-axis is labeled "Potential Energy" and is measured in kilojoules. The slope starts at 0 seconds with a plateau at 25 kJ. This plateau is labeled "Reactants." The slope then rises to a peak labeled "Activation Energy" at 78 kJ. Finally the slope drops to a plateau at 14 kJ and is labeled "Products."
What does the graph described above represent?
(1 point)
an exothermic reaction
an endothermic reaction
rate of Reaction graph
a phase change graph
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Endothermic reactions absorb a lot of energy. Exothermic reactions give off a lot of energy. Which type of reaction has a higher activation energy? Which one takes more energy to break up the bonds of the reactants?(1 point)
Exothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
Endothermic reactions have a higher activation energy. Exothermic reactions require more energy to break up the bonds of the reactants.
Endothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
Exothermic reactions have a higher activation energy. Exothermic reactions require more energy to break up the bonds of the reactants.
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Why is thermal energy (heat) required to freeze ice into crystals?(1 point)
Heat must be released by the reactants and the products.
Heat must be released by the products in order to convert from the reactants.
Heat must be absorbed by the products in order to convert from the reactants.
Heat must be absorbed by the reactants and the products.
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Cobalt ions form complex ions with water and chloride as shown in the reaction. The left side of the reaction is pink, and the right side of the reaction is blue.
Co(H2O)62+ + 4Cl– + heat ⇄ CoCl42–+ 6H2O
Which statement about the system at equilibrium is correct?
(1 point)
Adding water to a purple solution will turn it blue.
Adding hydrogen chloride (HCl) to a blue solution will turn it purple.
Cooling a purple solution will turn it pink.
Heating a blue solution will turn it purple.
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Why are rubber and metal both useful while making wire?(1 point)
Both are flexible, but one conducts electricity while the other insulates.
Both are flexible, but one reflects electromagnetic waves well while the other transmits them.
Both are good insulators, but one is flexible while the other is rigid.
Both are good insulators, but one is more ductile than the other.
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A pharmaceutical company wants to extract an ingredient from pomace supplied by a certain food processing plant. Which process is the most efficient with the lowest environmental impact?(1 point)
enzyme extraction
organic solvent extraction
catalyst extraction
high pressure, high temperature water extraction
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Which option is a modern reason for optimizing the mining process?(1 point)
reducing environmental impact
reducing waste
increasing production efficiency
increasing profits
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Use the reaction to answer the question.
Fe2O3 + 3H2SO4
How many atoms of oxygen will be found in the product(s) of the reaction?
(1 point)
4
15
12
3
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Use the table and equation to answer the question.
Element Atomic Mass (amu)
hydrogen 1
carbon 12
oxygen 16
CH4 + 2 O2 → CO2 + 2 H2O
The law of conservation of matter states that matter cannot be created nor destroyed. How does the balance equation above demonstrate this law?
(1 point)
The number of molecules, type of elements, and mass of reactants and products are equal.
The number of atoms, type of elements, and mass of reactants and products are equal.
The number of molecules, number of atoms, and type of elements are equal.
The number of molecules, number of atoms, and mass of reactants and products are equal.
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Elements A and B react according to the following balanced equation.
3A2 + 2B → 2A3B
The molar mass of element A is 4 g/mol. The molar mass of element B is 16 g/mol. When the initial mass of element A is 48 grams, which mass of element B should be present?
(1 point)
64 grams
192 grams
96 grams
128 grams
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Use the table of molar masses to answer the question.
Element Molar Mass (g/mol)
silicon 28.09
oxygen 16.00
How many molecules of silicon dioxide (SiO2) are there in a 15-gram sample?
(1 point)
1.251×10231 point 2 5 1 times 10 to the 23th power
2.049×10232 point 0 4 9 times 10 to the 23th power
1.503×10231 point 5 0 3 times 10 to the 23th power
6.022×10236 point 0 2 2 times 10 to the 23th power
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Which statement about the number of protons and neutrons in a nuclear change is correct?(1 point)
The total charge before and after the change remains the same, but the total atomic mass is different.
The total atomic mass before and after the change remains the same, but the total charge is different.
The relative numbers of protons and neutrons are the same before and after the change.
The relative numbers of protons and neutrons can differ before and after the change, but the total number of those particles remains the same.
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Which statement accurately describes nuclear fission? (1 point)
Fission is a process in which two or more nuclei combine to form a larger nucleus.
Fission is a process in which a large nucleus is split into smaller nuclei.
Fission is a process in which an unstable nucleus releases matter and energy.
Fission is a process in which two or more atoms combine chemically.
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A nucleus decays to produce a nucleus with one additional proton. Which type of decay did the nucleus undergo?(1 point)
beta-plus decay
gamma decay
alpha decay
beta-minus decay
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Which type of decay is a form of nuclear fission?(1 point)
gamma decay
alpha decay
beta-minus decay
beta-plus decay
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Why do some atmospheric gases act as greenhouse gases, while others do not?(1 point)
Naturally occurring gases do not act as greenhouse gases, while human-made gases do.
The industrial revolution changed the components of the atmosphere, causing some gases to become greenhouse gases.
Greenhouse gases have more than two atoms, allowing them to vibrate and release radiation, warming the atmosphere.
Non-greenhouse gases are made of only one element, like nitrogen or oxygen.
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Which option correctly identifies a cause and consequence of water pollution?(1 point)
cause: chlorofluorocarbons
consequence: depletion of ozone layer
cause: particulates
consequence: smog
cause: acid rain
consequence: destruction of crops
cause: runoff of pesticides
consequence: global warming
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Which outcome is the most likely result of eutrophication of a waterway?(1 point)
toxic bacteria in the water supply
reduced storm runoff
reduction of the algae population
overpopulation of aquatic plants
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Despite fracking being a controversial process in the fuel industry, it is still used today. Why?(1 point)
It reaches hard to get to oil and gas deposits.
There is little environmental harm done to the land.
It can be done on lands no one wants.
It is inexpensive to do.
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All 24 questions, please, I need this before midnight. Thanks to everyone n anyone for even giving a try.
1. Cs-Br
2. Fr–Cl = 2.46
3.Hotter molecules have more kinetic energy.
4.The reaction is exothermic.
5. More bond energy is absorbed on the reactants side than is released on the products side.
6. an exothermic reaction
7. Endothermic reactions have a higher activation energy. Endothermic reactions require more energy to break up the bonds of the reactants.
8. Heat must be released by the products in order to convert from the reactants.
9. Cooling a purple solution will turn it pink.
10. Both are flexible, but one conducts electricity while the other insulates.
11. high pressure, high temperature water extraction
12. reducing environmental impact
13. 15
14. The number of atoms, type of elements, and mass of reactants and products are equal.
15. 64 grams
16. 1.503×1023
17. The relative numbers of protons and neutrons can differ before and after the change, but the total number of those particles remains the same.
18. Fission is a process in which a large nucleus is split into smaller nuclei.
19. beta-minus decay
20. alpha decay
21. Greenhouse gases have more than two atoms, allowing them to vibrate and release radiation, warming the atmosphere.
22. cause: acid rain
consequence: destruction of crops
23. toxic bacteria in the water supply
24. It reaches hard to get to oil and gas deposits.
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