PHY S exam 3
If GaAs forms a semiconductor like Ge, which of the following elements will form a semiconductor like Si? (Hint: Look at the periodic table.) a. Al and P b. B and As c. C and Ge d. Ga and N
a. Al and P
In a bonding orbital between two atoms, where is the electron density the highest? (Where do you have the highest probability of detecting an electron?) a. in between the two atoms b. the density is evenly distributed around both atoms c. around the outside of the two atoms.
a. in between the two atoms
Which of the following is atomic matter rather than molecular or network matter? a. neon gas b. magnesium chloride c. water d. silver e. white gold
a. neon gas
How many electrons does Cl want to gain? Hint: How many are gained to form a stable noble gas electron configuration, ns2np6 (octet rule)? a. 0 b. 1 c. 2 d. 3
b. 1
Each molecule of methane has the formula CH4. If there are 4,000 carbon atoms present, how many hydrogen atoms will be required to convert all the carbon atoms into methane? a. 1,000 b. 2,000 c. 4,000 d. 16,000
d. 16,000
Which of the following is not why alloys are useful to us today? a. Alloys reduce weight in objects. b. Alloys have lower melting temperatures. c. Alloys are less malleable. d. Alloys have a higher conductivity rate.
d. Alloys have a higher conductivity rate.
True or false: Polyatomic ions form crystals.
true
True or false: Forming a positive ion with a noble gas configuration (ns2np6) from a nonmetal requires a tremendous amount of energy.
true. To form a positively charged ion with a noble gas configuration from a nonmetal means that up to seven valence s and p electrons may need to be removed. Since the ionization energy of each valence electron is high, the cost to remove that many would be exorbitant.
A very fast reaction has a very high activation energy.
False
Molecular orbitals are the same shape as atomic orbitals.
False
Fatty substances that are solid at room temperature are classified as oils. a. True b. False
b. False
Locate the elements palladium (Pd, atomic #46) and nickel (Ni, atomic #28) on the periodic table (Links to an external site.). If Pd is combined with Ni, which of the following characteristics will the product show at room temperature? a. transparent gas b. shiny, malleable solid c. opaque gas d. brittle, opaque solid e. non-conducting, transparent solid
b. shiny, malleable solid
Metals have higher ionization energies than nonmetals do.
false
The forces between the N2 molecules are very strong.
false
An ice cube melts in a glass of warm water. This is an example of which type of process? a. reversible b. irreversible c. impossible
irreversible
Each molecule of nitric acid has the formula HNO3. If there are 6000 oxygen atoms present and 6000 nitrogen atoms present, how many hydrogen atoms will be required to convert all of the oxygen atoms into nitric acid? a. 4000 b. 2000 c. 1000 d. 6000 e. 18000
b. 2000
Which type of atom has the highest ionization energy?
nonmetal
Metals have a greater tendency than nonmetals to lose electrons.
True
What are compounds between two different metals called? a. fusions b. alloys c. metallic bonds
b. alloys
What type of bond would exist between the carbon and the oxygen? a. metallic b. covalent c. ionic
b. covalent
Which type of energy is the most ordered? a. chemical potential energy b. thermal energy c. nuclear potential energy d. gravitational potential energy
d. gravitational potential energy
Entropy is a measure of the ________ of a system.
disorder
How many more electrons does unbound oxygen need to fill its 2nd shell? (You may find it helpful to draw the energy well on scratch paper.) a. 6 b. 1 c. none, the 2nd shell is full d. 8 e. 2
e. 2
What is the chemical formula for sulfur? a. S8 b. S2 c. S d. 8S e. SO2
a. S8
Given the electron configuration diagram, predict how many electrons Mg would be expected to lose in ionic compounds. Hint: How many are lost to form a stable noble gas electron configuration, ns2np6 (octet rule)? a. 1 b. 2 c. 3 d. 4
b. 2
What combinations of atoms make covalent bonds? a. All the atoms are metal b. All of the atoms are nonmetal c. Combinations of both metal and nonmetal atoms d. Any combination of atoms
b. All of the atoms are nonmetal
What happens to the energy of the system as this compound is formed? a. The energy increases. b. The energy decreases. c. The energy remains the same.
b. The energy decreases.
Which of the following would best describe the room temperature characteristics of the substance that results from the reaction between magnesium (Mg) and oxygen (O)? a. The elements listed are very unlikely to react with one another. b. a brittle, transparent, electrically non-conducting solid c. a transparent gas d. a malleable solid e. an electrically conducting alloy
b. a brittle, transparent, electrically non-conducting solid
Which of the following processes is closest to an ideal reversible process? a. a pendulum swinging b. an ice cube floating in a glass of water at zero degrees c. two cars colliding d. using a toaster to make toast e. a ripe peach rotting
b. an ice cube floating in a glass of water at zero degrees
Rank the following according to their strength, weakest first, strongest last. a. covalent bonding, hydrogen bonding, dipole-dipole interactions, dispersion forces b. dispersion forces, dipole-dipole interactions, hydrogen bonding, covalent bonding c. hydrogen bonding, covalent bonding, dispersion forces, dipole-dipole interactions d. dipole-dipole interactions, dispersion forces, covalent bonding, hydrogen bonding e. hydrogen bonding, dipole-dipole interactions, dispersion bonding, covalent bonding
b. dispersion forces, dipole-dipole interactions, hydrogen bonding, covalent bonding
In order for an energetically favorable chemical reaction to occur a. entropy must increase as a result of the reaction. b. energy must decrease as a result of the reaction. c. energy and entropy must both increase. d. energy and entropy must both decrease.
b. energy must decrease as a result of the reaction.
NH4NO3 (solid) + H2O (liquid) ⇒ NH4+ + NO3- in water solution, energy absorbed: a. favorable energy change b. favorable entropy change c. both
b. favorable entropy change
N2 has a triple bond and is a gas at room temperature. The triple bond is a very strong bond.
true
True or false: It is energetically favorable for nonmetals to share electrons.
true. Because of their strong attraction for electrons, nonmetals are attracted to the electrons of other atoms.
A material that is made up of one type of molecule, where each molecule is made of 2 different types of atoms is still a pure substance.
true
Which of the following is not used as a measurement technique for identifying chemical substances? a. color spectroscopy b. vibrational spectroscopy c. electronic spectroscopy d. crystallography e. mass spectroscopy
a. color spectroscopy
What happens to the spacing between the energy of one molecular orbital and the next one immediately above or below it as the number of atoms that come together increases? a. The spacing between energy levels increases. b. The spacing between energy levels decreases. c. The spacing stays the same.
b. The spacing between energy levels decreases.
In the future, engineers will be able to design a car that is 100% efficient. a. T B. F
False
In an irreversible process, what happens to the overall disorder of the universe? a. It increases. b. It becomes infinite. c. It decreases. d. It becomes zero. e. It is conserved.
a. It increases.
What happens to the overall entropy in the universe as this compound is formed? a. The entropy increases. b. The entropy decreases. c. The entropy remains the same.
a. The entropy increases.
Which of the following would best describe the room-temperature characteristics of an ionic substance? a. brittle, transparent, electrically non-conducting solid b. a malleable solid c. electrically conducting alloy d. transparent gas
a. brittle, transparent, electrically non-conducting solid
How would you describe the melting point of a substance formed by a molecular ion? a. high b. low c. extremely low
a. high
What classification of matter is magnesium chloride? a. network matter b. molecular matter c. atomic matter
a. network matter
Which of the following best explains why metals are opaque and shiny? a. Because the energy levels are so close that the photons cannot get through. b. Because the electrons form a sea that repels the photons c. Because there are so many empty orbitals that the electrons can absorb and emit any frequency of light.
c. Because there are so many empty orbitals that the electrons can absorb and emit any frequency of light.
Which of the following is an ionic compound? a. CO2 b. O2 c. MgF2 d. NH3
c. MgF2
What happens to the number of molecular orbitals as the number of atoms that come together increases? a. The number of molecular orbitals increases. b. The number of molecular orbitals decreases. c. There's not enough information to answer this question.
a. The number of molecular orbitals increases.
Characterize the following reactions as occurring with a favorable energy change when the reactants become the products, a favorable entropy change when the reactants become the products, or both. Remember, gases have more disorder than liquids, which have more disorder than solids. 2H2 (gas) + O2 (gas) ⇒ 2H2O (gas), energy is given off: a. favorable energy change b. favorable entropy change c. both
a. favorable energy change Thermal energy is released. This means the products have a lower overall energy than the reactants, which is favorable.
Magnesium chloride forms a solid in which two chloride ions are found for every magnesium ion, but no discrete molecules are observed in the solid. What is the simplest formula for this compound? a. Mg2Cl4 b. MgCl c. MgCl2 d. Mg2Cl2
c. MgCl2
In which of the following processes is the end product more ordered than the reactants? (In which process does entropy decrease in the system?) a. NaHCO3 (solid) + C2H4O2 (liquid)=C2H3NaO2 (solid)+ H2O(liquid) + CO2 (gas) b. 2C7H5N3O6 (solid) = 3N2 (gas) + 7CO(gas) + 5H2O (gas) + 7 C (solid) c. C6H12O6 (solid) + 6O2 (gas) = 6CO2 (gas) + 6H2O (liquid) d. 2C8H18 (liquid) + 25O2 (gas) = 16CO2 (gas) + 18H2O (gas) e. 2H2 (gas) + O2 (gas) = 2 H2O (gas)
e. 2H2 (gas) + O2 (gas) = 2 H2O (gas)
True or false: Nonmetals have a large number of s- and p-type valence electrons relative to metals.
true. Nonmetals have between four and seven of these kind of electrons while metals have only one to three.
Mica is a silicate that has strong bonds throughout its entire structure.
False
Why are metals opaque? a. Because the atoms are closer together than the wavelength of light. b. Because metals are good conductors. c. Because metals have high melting and boiling points and it takes a lot of energy to move a photon. d. Because metals have empty, overlapping orbitals for their electrons that create very closely spaced energy levels. e. Because metals are malleable, so photons cannot get through the moving nuclei.
d. Because metals have empty, overlapping orbitals for their electrons that create very closely spaced energy levels.
What happens to the entropy of the universe as the products are formed? a. Chemical potential energy is converted into kinetic energy, resulting in a decrease in entropy. b. Chemical bonds are formed, resulting in a decrease in total entropy. c. The total entropy stays the same. d. Chemical potential energy is converted into thermal energy resulting in an increase in entropy. e. Thermal energy is converted into electromagnetic energy, resulting in a decrease in total entropy.
d. Chemical potential energy is converted into thermal energy resulting in an increase in entropy.
A car can't convert all the energy from its fuel to macroscopic kinetic energy. Why? a. Energy would be conserved. b. Energy would not be conserved. c. Entropy would increase. d. Entropy would decrease. e. Entropy would remain the same.
d. Entropy would decrease.
Which of the following fatty acids is best for human health? a. Fatty acids that only have single bonds between carbon atoms. b. Fatty acids that have one or more "straight" trans-double bonds between carbon atoms. c. All are equally bad for your health. d. Fatty acids that have one or more "bent" cis-double bonds between carbon atoms.
d. Fatty acids that have one or more "bent" cis-double bonds between carbon atoms.
Which of the following is not a compound? a. nitrous oxide (N2O) b. oxygen molecule (O2) c. water molecule (H2O) d. sulfur dioxide (SO2) e. rust (Fe2O3)
b. oxygen molecule (O2)
The energies of the orbitals that form when metals interact are very widely spaced in energy.
False
Which type of atom has valence electron states high enough in energy that they overlap with the stacked-together molecular orbitals that form the conduction band?
metal
Which type of atom has valence electrons higher in the energy well?
metal
A reversible process does what to the total disorder in the universe? a. The total disorder decreases. b. The total disorder increases. c. The total disorder does not change
the total disorder does not change
Which of the following pairs would you expect to be covalently bonded? a. S and Br b. P and Ca c. Co and Al d. Ar and Cl
a. S and Br
Dispersion forces are stronger than covalent bonds.
false
The various forms of energy can be ranked according to their level of what? a. organization b. energy c. power
a. organization
Covalent bond
a force that holds atoms together to make a molecule in the first place, not a force between molecules
dipole-dipole interaction
a force that holds molecules together when that molecule has positive and negative ends
In the chemical equation C6H12O6 + 3O2 ⇒ 3CO2 + 6H2O, how many oxygen atoms are on the right side of the equation? a. 3 b. 7 c. 12 d. 8
c. 12
True or false: Molecular ions are poor conductors of electricity in solid and liquid forms.
false
C3H8 (gas) + 5O2 (gas)⇒ 3CO2 (gas) + 4H2O (vapor), energy given off: a. favorable energy change b. favorable entropy change c. both
c. both
Which of the following is a true statement about melting and boiling points in materials made of covalent molecules? a. Molecules that contain triple bonds are the most likely to be gases at room temperature. b. Molecules that are polar have lower melting and boiling points than nonpolar molecules. c. Dispersion forces (Van der Waals forces) have no impact on melting and boiling points. d. Molecules that contain double bonds melt and boil at higher temperatures because the bonds are stronger. e. Hydrogen bonding between molecules increases melting and boiling points.
e. Hydrogen bonding between molecules increases melting and boiling points.
How does a catalyst affect a reaction? a. It changes anti-bonding orbitals into bonding orbitals. b. It lowers the band gap. c. It raises the activation entropy. d. It increases the energy of the transition state. e. It lowers the activation energy.
e. It lowers the activation energy.
Two or more different elements that are chemically combined are always what kind of substance? a. a mineral b. an ion c. solids d. a mixture e. a compound
e. a compound
True or false: A valence electron in a nonmetal has a very low ionization energy.
false. As you go from left to right across a period, the ionization energy increases. Nonmetals are on the right side of the periodic table, so they have high ionization energies.
Complete conversion of one form of energy to another can occur only in which direction? a. from lower to higher organized forms b. from higher to lower organized forms
from higher to lower organized forms
Pure aluminum metal has a melting temperature of 660˚C. The process of liquid aluminum freezing to solid aluminum at this temperature is ________. a. reversible b. irreversible
irreversible
dispersion forces
a force that holds molecules together when the molecule is nonpolar
What happens to the valence electrons as the product (MgO) is formed? a. The orbitals spread out into the whole solid and overlap. b. The orbitals of both atoms' valence electrons change shape so that the electrons are shared equally between the atoms. c. The magnesium atoms' valence electrons are effectively transferred to oxygen. d. The electrons move to new orbitals that are higher in energy than the individual atomic orbitals. e. The oxygen atoms' valence electrons are effectively transferred to magnesium.
c. The magnesium atoms' valence electrons are effectively transferred to oxygen.
A metal can best be described as a. a network solid consisting of individual negatively-charged atoms. b. a network solid consisting of positively-charged and negatively-charged ions. c. a network solid consisting of positively-charged nuclei in a sea of electrons. d. a molecular solid consisting of charged atoms. e. an ionic solid consisting of covalently-bonded atoms.
c. a network solid consisting of positively-charged nuclei in a sea of electrons.
C6H12O6 (solid) + 3O2 (gas) ⇒ 3CO2 (gas) + 6H2O (vapor), energy given off: a. favorable energy change b. favorable entropy change c. both
c. both
A window air conditioner is normally placed in a window so the hot air from the back blows outside. What would happen if the air conditioner were placed in the middle of a closed room and turned on? a. The room would heat up because all of the energy absorbed by the air conditioner, both thermal and electrical potential, is released back into the room as thermal energy. b. The room would heat up because the electrical potential energy loses entropy while the room gains entropy. c. The room would cool down because the electrical potential energy from the outlet decreases the ambient thermal energy in the room. d. The room would cool down because as the entropy of the electrical potential energy increases, the entropy of the room must decrease to compensate. e. The temperature of the room would stay the same because internal energy is conserved.
a. The room would heat up because all of the energy absorbed by the air conditioner, both thermal and electrical potential, is released back into the room as thermal energy.
Which of the following set of properties is most likely those associated with methane, a covalently bonded compound? a. gas at room temperature, colorless, does not conduct electricity when solid b. solid at room temperature, opaque, good electrical conductor c. solid at room temperature, transparent, electrical conductor when dissolved in water
a. gas at room temperature, colorless, does not conduct electricity when solid
Which of the following tends to have the highest melting and boiling points? a. network matter b. atomic matter c. molecular matter
a. network matter
Which is the best definition of an alloy? a. solid mixture of metals b. liquid mixture of metals c. liquid mixture of compounds d. solid mixture of compounds e. two or more kinds of atoms
a. solid mixture of metals
We see a large amount of order in the world around us, from life to currents in the air and ocean. How is this consistent with the law of increasing disorder? a. It is because these things don't represent order. b. It is because the law of increasing disorder doesn't apply to living things. c. It is because the sun provides additional high-order energy to the world to create this order. d. It isn't, because the law of increasing disorder only applies to closed systems.
c. It is because the sun provides additional high-order energy to the world to create this order.
What are the electrons in a covalent bond doing? a. Transferred from one atom to another b. Shared between all of the atoms present c. Shared between specific pairs of atoms
c. Shared between specific pairs of atoms
Ammonium nitrate (NH4NO3), a common fertilizer, is an ionically bonded substance involving two polyatomic ions, ammonium (NH4+) and nitrate (NO3-). Ammonium nitrate dissolves well in a polar solvent such as water. Which of the following statements best describes what happens when this fertilizer dissolves in water? a. All the bonds between atoms are broken, allowing the individual atoms to float in the water. b. The compound doesn't break up at all. The entire compound floats in the water still bound together as ammonium nitrate. c. The compound breaks up into the two oppositely charged ions. The ions do not break apart. d. The compound breaks up completely and causes nitrogen gas, oxygen gas, and hydrogen gas to form.
c. The compound breaks up into the two oppositely charged ions. The ions do not break apart.
Which of the following is not a characteristic of a metal or alloy? a. electrically conductive b. malleable c. brittle d. thermally conductive
c. brittle
Can sulfur be considered a compound? Why? a. Yes, it is composed of only one type of atom. b. No, it is composed of more than one type of atom. c. Yes, it is composed of more than one type of atom. d. No, it is composed of only one type of atom.
d. No, it is composed of only one type of atom.
When you compare the band gap for a red and a blue LED, what is true? a. The blue LED has the smallest band gap. b. The color of light doesn't have anything to do with the band gap. c. The band gaps are equal as long as the battery powering them is the same. d. The red LED has the smallest band gap.
d. The red LED has the smallest band gap.
If you compare metals with ionic compounds, what do they have in common? a. Conductivity b. They way they interact with light c. The way they respond to forces d. Their melting temperatures are similar
d. Their melting temperatures are similar
The gasoline engine of an automobile is considerably less than 100% efficient. This means that not all of the energy in the gasoline is turned into kinetic energy of the car. Which of the following best explains why? a. Engineers and scientists have not yet managed to make it more efficient, but there is no scientific reason it cannot be 100% efficient. b. Actually the automobile engine is nearly 100% efficient as long as the automobile is traveling on the level. When it climbs up a hill, however, the efficiency drops because of the changing gravitational potential energy. c. All engines (that is electric motors, gasoline engines, steam power generators burning gas, oil, and so forth) have exactly the same efficiency, which is, of course, less than 100%. d. There is too much friction in the engine and the rest of the automobile. If it were not for this friction the efficiency would be 100%. e. Some of the chemical potential energy in the gasoline must become ambient thermal energy if the rest is to supply the kinetic energy of the automobile. This means some energy must be wasted.
e. Some of the chemical potential energy in the gasoline must become ambient thermal energy if the rest is to supply the kinetic energy of the automobile. This means some energy must be wasted.
True or false: Nonmetal nuclei have a strong attraction for valence electrons.
true. The high ionization energy of nonmetals is evidence for a strong electron-nuclear attraction.
Energy and entropy are both involved in chemical reactions.
True
In minerals, the underlying atomic structure gives rise to large-scale properties observable with the naked eye.
True
Quartz is a silicate that has strong bonds throughout its entire structure.
True
Uranium-238 alpha decays, emitting a helium-4 nucleus. What is the mass number of the product? a. 234 b. 230 c. 246 d. 238 e. 242
a. 234
What influences melting point? a. All of the below b. Length of the molecule c. Number of double bonds d. Type of double bond (cis vs trans) e. Shape of the molecule
a. All of the below
What happens to the melting temperature as the size of the molecule increases? a. The melting temperature increases with size. b. The melting temperature decreases with size. c. The melting temperature doesn't show any noticeable trend.
a. The melting temperature increases with size.
When you compare the mass of the products to the mass of the reactants in a fission reaction, what do you find? (Note the question is asking about mass, not mass number.) a. The reactants have more mass. b. The products have more mass. c. The mass is the same on each side.
a. The reactants have more mass.
Why do natural unsaturated fats have a lower solidification temperature than saturated fats? a. They have curved hydrocarbon tails that keep individual molecules farther apart. b. They have curved hydrocarbon tails that keep individual molecules closer together. c. They have straight hydrocarbon tails that keep individual molecules farther apart. d. They have straight hydrocarbon tails that keep individual molecules closer together.
a. They have curved hydrocarbon tails that keep individual molecules farther apart.
Unsaturated fats are considered an essential part of a healthy diet. a. True b. False
a. True
Which of the following correctly applies the law of increasing disorder to an air conditioner? a. Air conditioners violate the Law of Increasing Disorder because a heat flow from a cold region to a hot one represents a decrease of disorder. b. It is true that the heat flow from the cold region to the hotter region increases order, but this is made up for by increasing the disorder of energy from another source. c. The Law of Increasing Disorder is not involved in this situation because the Law of Increasing Disorder does not apply to heat flow. d. All the energy that leaves the cold region shows up in the hotter region, and therefore there is no change of disorder. e. There is no violation of the Law of Increasing Disorder because a heat flow from a cold region to a hot region represents an increase of disorder.
b. It is true that the heat flow from the cold region to the hotter region increases order, but this is made up for by increasing the disorder of energy from another source.
What happens to the change in mass? a. Mass is gained when the strong force binds the nucleons together. b. Mass is lost when the strong force binds the nucleons together. c. Nothing happens—the mass was unchanged.
b. Mass is lost when the strong force binds the nucleons together.
When you compare saturated with unsaturated fatty acids containing the same number of carbon atoms, what is true? a. Saturated fatty acids have lower melting points. b. Saturated fatty acids have more hydrogen atoms. c. Saturated fatty acids are more curved. d. Saturated fatty acids have more oxygen atoms. e. Saturated fatty acids have more double bonds.
b. Saturated fatty acids have more hydrogen atoms.
What happens to the valence electrons as an ionic compound is formed? a. The orbitals spread out into the whole solid and overlap. b. The metal atoms' valence electrons are effectively transferred to the nonmetal. c. The electrons move to new orbitals that are higher in energy than the individual atomic orbitals. d. The nonmetal atoms' valence electrons are effectively transferred to the metal. e. The orbitals of both the metal and nonmetal atoms' valence electrons change shape so that the electrons are shared equally between the atoms.
b. The metal atoms' valence electrons are effectively transferred to the nonmetal.
Nuclear fission is when a. protons and neutrons decay into simpler particles. b. a large nucleus breaks apart into smaller pieces. c. small nuclei combine to form a larger nucleus. d. electrons combine with protons to form neutrons.
b. a large nucleus breaks apart into smaller pieces.
What is the approximate range of the nuclear strong force? (In other words, what is the distance over which the strong force is significant?) a. about the size of an atom b. about the size of a nucleus c. indefinite—nuclei feel each other's influence over arbitrary large distances d. much smaller than the size of a nucleus
b. about the size of a nucleus
Isotopes of an element are different atoms of the element that a. have the same number of protons, but differ in atomic number. b. have the same number of protons, but differ in mass number. c. have the same number of neutrons, but differ in mass number. d. have the same number of neutrons, but differ in atomic number. e. have the same mass number, but differ in atomic number.
b. have the same number of protons, but differ in mass number.
The Second Law of Thermodynamics (Law of Increasing Disorder) places limits on the efficiency of energy conversion. Which of the following is allowed? a. 100% conversion of chemical potential energy to kinetic energy b. 100% conversion of sunlight to kinetic energy c. 100% conversion of electricity to ambient temperature thermal energy d. 100% conversion of ambient temperature thermal energy to chemical potential energy e. 100% conversion of ambient temperature thermal energy to kinetic energy
c. 100% conversion of electricity to ambient temperature thermal energy
Which of the following substances is most likely to be a pure element? a. carbon dioxide b. wood c. copper d. air e. milk
c. copper
Ionic compounds are formed between a metal and a a. ion particle. b. mineral. c. nonmetal.
c. nonmetal.
The process that produces most of the explosive energy of a hydrogen bomb and that is believed to be responsible for the energy released by the sun is called a. radioactivity. b. artificial transmutation. c. nuclear fusion. d. electron-positron annihilation. e. nuclear fission.
c. nuclear fusion.
Which of the following is the best description of activation energy? a. the energy that is released when a molecular orbital forms b. the energy that must be taken out of a system before a reaction can take place c. the energy that must be put into a system before a reaction can take place. d. the energy at which the forward and reverse reaction rates are equal
c. the energy that must be put into a system before a reaction can take place.
The oxidation state of an atom refers to a. the number of bonds formed in a ionic bond. b. the number that identifies which oxide has been formed. c. the number of electrons gained or lost when an ionic bond is formed. d. the number of oxides that can be formed.
c. the number of electrons gained or lost when an ionic bond is formed.
Fish that swim in the cold North Atlantic would have what type of fatty acid in their blood? a. saturated fatty acids with short tails b. saturated fatty acids with long tails c. unsaturated acids with lots of double bonds
c. unsaturated acids with lots of double bonds
What is the charge of iron (Fe) in the compound Fe2O3? a. −2 b. +2 c. −3 d. +3
d. +3
Why is a high temperature required for nuclear fusion to occur? a. High temperatures cause the electromagnetic force to change from a repulsive force to an attractive force which helps the strong force combine the two nuclei. b. High temperatures are required to keep the fusion fuel, deuterium and tritium, stable. c. High temperatures magnify the strong force attraction and allow fusion to occur more readily. d. High temperatures are required to allow the nuclei to have enough kinetic energy to overcome the electromagnetic repulsion and have the strong force attraction take place.
d. High temperatures are required to allow the nuclei to have enough kinetic energy to overcome the electromagnetic repulsion and have the strong force attraction take place.
Both fission and fusion can result in a release of energy. Why? a. The strong force is attractive over short distances and repulsive at larger distances. b. Either combining large nuclei or splitting small nuclei results in an increase in energy. This energy is released as heat. c. Any change to a nucleus is going to convert mass into energy. d. The nuclei of atoms near the middle of the periodic table have the least energy and the nucleons with the smallest mass.
d. The nuclei of atoms near the middle of the periodic table have the least energy and the nucleons with the smallest mass.
Carbon-14 (146C614C) is not stable and it spontaneously decays into nitrogen-14 (147N714N) and an electron by a radioactive beta-decay. Which of the following is true about the decay? a. Carbon-14 has more entropy than the products. b. The mass of the nitrogen-14 plus the electron will be greater than the mass of the carbon-14 atom. c. One of the protons in carbon-14 changed into a neutron. d. The total number of nucleons stays the same. e. The total charge of the carbon-14 is greater than the total charge of the products.
d. The total number of nucleons stays the same.
Which of the following is unimportant in the determining the characteristics of fatty acids? a. covalent bonds b. dispersion forces c. hydrogen bonds d. ionic bonds
d. ionic bonds
An unstable nucleus which has a tendency to spontaneously change its form with the emission of high-energy particles or photons is said to be a. an isotope. b. annihilated. c. ionized. d. radioactive. e. critical.
d. radioactive.
The purpose of the control rods in a nuclear fission reactor is a. to act as spacers to keep the fuel elements apart. b. to increase the number of neutrons by causing nuclear reactions in the control rods, so that more nuclei in the fuel will undergo fission. c. to slow down the neutrons, since slower neutrons have a higher probability of causing fission. d. to absorb neutrons, thus limiting the number of nuclei undergoing fission. e. to contain material to be transformed into new fissionable fuel by neutron irradiation.
d. to absorb neutrons, thus limiting the number of nuclei undergoing fission.
Would a double bond between two carbon atoms increase or decrease the number of hydrogen atoms that could bond to carbon in these molecules?
decrease
Which of the following is a correct comparison of metals and semi-conductors? a. A semi-conductor's molecular orbitals overlap while a metals don't. b. Metals have a larger band gap than semi-conductors. c. Metals have more valence electrons than semi-conductors. d. Metals have larger electrical resistance than semi-conductors. e. A metal's resistance increases when temperature increases while a semi-conductor's resistance decreases.
e. A metal's resistance increases when temperature increases while a semi-conductor's resistance decreases.
The process known as nuclear fission is primarily responsible for a. the explosion of a hydrogen bomb. b. more than one of these. c. the energy produced by the sun. d. electron-positron annihilation. e. the energy produced by a nuclear reactor.
e. the energy produced by a nuclear reactor.
