Physical Science Exam 3

The purpose of the control rods in a nuclear fission reactor is Select one: A. to slow down the neutrons, since slower neutrons have a higher probability of causing fission. B. to absorb neutrons, thus limiting the number of nuclei undergoing fission. C. to increase the number of neutrons by causing nuclear reactions in the control rods, so that more nuclei in the fuel will undergo fission. D. to act as spacers to keep the fuel elements apart. E. to contain material to be transformed into new fissionable fuel by neutron irradiation.

B

Uranium-238 alpha decays, emitting a helium-4 nucleus. What is the mass number of the product? Select one: A. 230 B. 234 C. 238 D. 242 E. 246

B

What happens to the spacing between the energy of one MO and the next one immediately above or below it as the number of atoms that come together increases? A. Increases B. decreases C. remains the same

B

Which type of atom has the highest ionization energy? A. metal B. non-metal

B

Each molecule of methane has the formula CH4 If there are 4000 carbon atoms present how many hydrogen atoms will be required to convert all of the carbon atoms into methane? A. 400 B. 4000 C. 16000 D. 1600

C

How many protons does tritium, 3H, have? A. 1 B. 2 C. 3

A

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? A. metal B. non-metal

A

Which type of atom has valence electrons higher in the energy well? A. metal B. non-metal

B

Which type of energy listed below is the most ordered? Select one: A. Nuclear potential energy B. Gravitational potential energy C. Thermal energy D. Chemical potential energy E. Impossible to tell without more information about the process.

B

Would a double bond between two carbon atoms increase or decrease the number of hydrogen atoms that could bond to carbon in these molecules? A. Increase B. Decrease

B

A sample of radioactive gas is produced. After 20 minutes, only 1/4 of the original gas remains. What is the half-life of the gas? ______ A. 1/2 min B. 5 min C. 10 min D. 20 min E. 40 min

C

A sample of radioactive material with a half-life of 6 hours sits for a day (24 hours). How much of the original radioactive material remains? ___ A. none B. 1/24 C. 1/16 D. 1/4 E. 1/2

C

How many double bonds exist between carbon atoms in these unsaturated fatty acids? A. Zero B. One C. One or More D. Two

C

How many electrons would sulfur need to gain to satisfy the octet rule? A. 0 B. 1 C. 2 D. 3

C

If GaAs forms a semiconductor like Ge, which of the following elements will form a semiconductor like Si? A. C and Ge B. B and As C. Ga and N D. Al and P

D

What would be the charge of calcium, Ca, in order to satisfy the octet rule? Hint: look at the column number. A.-2 B.-1 C.+1 D.+2

D

What happens to the entropy of the universe as the products are formed? Select one: A. The total entropy stays the same. B. Thermal energy is converted into electromagnetic energy resulting in a decrease in total entropy. C. Chemical bonds are formed resulting in a decrease in total entropy. D. Chemical potential energy is converted into kinetic energy resulting in a decrease in entropy. E. Chemical potential energy is converted into thermal energy resulting in an increase in entropy.

E

Because it is possible to separate the atoms back into different areas, the process is reversible. A. True B. False

B

In carbon tetra-chloride, CCl44, what is true about the charge distribution? Select one: A. The carbon will be more negative than the chlorine. B. The chlorine will be more negative than the carbon. C. The chlorine and carbon would be equally negative. D. The atoms will become positive and negative ions. E. It is impossible to predict how the electrons will distribute themselves in this type of bond.

B

Which of the following is a correct comparison of metals and semi-conductors? Select one: A. Metals have a larger band gap than semi-conductors. B. Metals' resistance increases when temperature increases while a semi-conductors resistance decreases. C. Semi-conductors' molecular orbitals overlap while metals' don't. D. Metals have more valence electrons than semi-conductors. E. Metals have larger electrical resistance than semi-conductors.

B

In an irreversible process, the overall disorder of the universe Select one: A. is constant. B. decreases. C. increases. D. is zero. E. becomes infinite.

C

Now ask yourself how many metal atoms (potassium) are needed to give all of the electrons that the atoms (sulfur) want to take? A.0 B.1 C.2 D.3

C

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, (octet rule) A. Zero B. One C. Two D. Three

C

What classification of matter is magnesium chloride? A. Atomic matter B. Molecular matter C. Network matter

C

What is the likelihood that the gases would regain the order they originally had if we left the system alone for a long time? A. There is a very high likelihood that the gases would spontaneously unmix B. There is a about a 50% percent chance the gases would spontaneously unmix C. There is virtually no chance the gases would spontaneously unmix

C

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. Mg2Cl B. MgCl2 C. 2MgCl

B

Both fission and fusion can result in a release of energy. Why? Select one: A. The strong force is attractive over short distances and repulsive at larger distances. B. Any change to a nucleus is going to convert mass into energy. C. The nuclei of atoms with a mass of about 50 have the smallest average nucleon mass and the least energy. D. Either combining large nuclei or splitting small nuclei results in an increase in energy. This energy is released as heat.

C

For the pictures of molecules below, the gray balls represent carbon atoms and the white balls are hydrogen atoms. The molecules belong to a family called the hydrocarbons. These questions test if you can recognize patterns in molecular families and bonding around carbon atoms and then reason from them to make predictions. A. CH3 B. 2CH2 C. C2H4 D. C2H6

C

Which of the following fatty acids is best for human health? Select one: 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. Fatty acids that have one or more 'bent' cis-double bonds between carbon atoms. D. All are equally bad for your health.

C

Which of the following tends to have the highest melting and boiling points? Select one: A. Atomic matter B. molecular matter C. network matter

C

Which of the following would best describe the characteristics of covalent materials? Select one: A. A brittle, transparent solid with a very high melting point. B. A shiny, malleable solid with a very high melting point. C. A non-conducting material with low melting and boiling points, likely liquid or gas at room temperature. D. A brittle, opaque solid with a very high melting point. E. A non-conducting solid at room temperature that will conduct if melted or dissolved.

C

A car can't convert all of 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

Which of the following processes is closest to an ideal reversible process? Select one: A. Two cars colliding. B. Using a toaster to make toast. C. A real pendulum swinging. D. A ripe peach rotting. E. An ice cube floating in a sealed insulated container of water at zero degrees.

E

Which of the following would best describe the room temperature characteristics of the magnesium oxide? Select one: A. Brittle, opaque, solid. B. Electrically conducting alloy. C. Transparent gas. D. A malleable solid. E. Brittle, transparent, electrically non-conducting solid.

E

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) Select one: A. The products have more mass B. The reactants have more mass C. The mass is the same on each side

B

What best describes how oxygen molecules would behave if mixed with water? Select one: A. They would dissolve well because they are polar. B. They would dissolve well because they are not polar. C. They would dissolve poorly or not at all because they are polar. D. They would dissolve poorly or not at all because they are not polar. E. They would dissolve well because they are ionic.

D

Which of the following is not a compound? A. sulfur dioxide B. nitrous oxide C. water molecule D. oxygen molecule E. rust

D

How many electrons would potassium, K, need to get rid of to satisfy the octet rule? Hint: Draw an energy well diagram. A.0 B.1 C.2 D.3

B

Metals have higher ionization energies than non-metals do. Select one: A. True B. False

B

Pure aluminum metal has a melting temperature at 660 °C. The process of liquid aluminum freezing to solid aluminum at this temperature is ... A. reversible B. irreversible

B

What happens to the valence electrons as the product (MgO) is formed? Select one: A. The orbitals spread out into the whole solid and overlap. B. The magnesium atoms' valence electrons are effectively transferred to oxygen. C. The oxygen atoms' valence electrons are effectively transferred to magnesium. D. The orbitals of both atoms' valence electrons change shape so that the electrons are shared equally between the atoms. E. The electrons move to new orbitals that are higher in energy than the individual atomic orbitals.

B

What would be the charge of bromine, Br, in order to satisfy the octet rule? Hint: look at the column number. A.-2 B.-1 C.1 D.2

B

When some Ca(NO3)2 dissolves in water which picture best represents what the solution looks like? (Note, the balls are not meant to indicate charge or lack of charge.) A B C

B

Which of the following is NOT why alloys are useful to us today? Alloys Select one: A. have lower melting temperatures. B. have a higher conductivity rate. C. are less malleable. D. reduce weight in objects.

B

When are molecules conductors of electricity? A. When they combine with metal atoms to form salts. B. When they combine with other non-metal atoms. C. When they combine with metals and are then melted or dissolved D. Never.

C

Why are metals opaque? Select one: A. because the atoms are closer together than the wavelength of light B. because metals are good heat conductors C. because metals are malleable D. because metals have high melting and boiling points E. because metals have empty, overlapping orbitals for their electrons

E

What happens to the number of MO's as the number of atoms that come together increases? A. Increases B. Decreases C. Remains the same

A

When you compare saturated with unsaturated fatty acids containing the same number of carbon atoms, what is true? Select one: A. Saturated fatty acids have more hydrogen atoms. B. Saturated fatty acids have more oxygen atoms. C. Saturated fatty acids are more curved. D. Saturated fatty acids have lower melting points. E. Saturated fatty acids have more double bonds.

A

Which of the following is atomic matter rather than molecular or network matter? Select one: A. Neon gas B. water C. magnesium chloride D. silver E. white gold

A

Why is a high temperature required for nuclear fusion to occur? Select one: A. 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. B. High temperatures magnify the strong force attraction and allow fusion to occur more readily. C. High temperatures are required to keep the fusion fuel, deuterium and tritium, stable. D. 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.

A

How many neutrons does tritium have? A. 1 B. 2 C. 3

B

It is possible to do work and sort the molecules into their separate containers. A. True B. False

A

Each molecule of nitric acid has the formula HNO33. 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? Select one: A. 1000 B. 2000 C. 4000 D. 6000 E. 18000

B

For each double bond, how many fewer hydrogen does the molecule have? A. The number of hydrogen decreases by 1 B. The number of hydrogen decreases by 2

B

How many electrons does Cl want to gain? Hint: how many are gained to form a stable noble gas electron configuration, (octet rule)? A. Zero B. One C. Two D. Three

B

In order for a chemical reaction to occur: Select one: A. Energy must decrease as a result of the reaction. B. Entropy must increase as a result of the reaction. C. Energy and entropy must both increase. D. Energy and entropy must both decrease. E. Energy must decrease and entropy must increase.

B

Locate the elements palladium (Pd, atomic #46) and nickel (Ni, atomic #28) on the periodic table. If Pd is combined with Ni, which of the following characteristics will the product show at room temperature? Select one: A. Non-conducting, transparent solid. B. Shiny, malleable solid. C. Transparent gas. D. Brittle, opaque solid. E. Opaque gas.

B

Look at Figures 1 and 2 below. Figure 1 shows that gas molecules are present inside the box. Figure 2 shows that there is a vacuum (no gas molecules present) inside of the box. If the two figures represent snapshots in time of an irreversible process, which figure came first and why? A. Figure 1: Because the gas molecules do not like to be confined and will leave the box. B. Figure 1: Because there is a hole allowing the molecules to escape. C. Figure 2: Because molecules rush inside the box to get rid of the vacuum. D. Figure 2: Because an empty box is more ordered.

D

The 2nd Law of Thermodynamics (Law of Increasing Disorder) places limits on the efficiency of energy conversion. Which of the following is allowed? Select one: A. 100% conversion of ambient temperature thermal energy to kinetic energy. B. 100% conversion of chemical potential energy to kinetic energy. C. 100% conversion of sunlight to kinetic energy. D. 100% conversion of electricity to ambient temperature thermal energy. E. 100% conversion of ambient temperature thermal energy to chemical potential energy.

D

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. 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. 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%. C. All engines (that is electric motors, gasoline engines, steam power generators burning gas or oil, etc) have exactly the same efficiency, which is, of course, less than 100%. D. 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. Actually the automobile engine is nearly 100% efficient as long as the automobile is traveli

D

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 isn't because the Law of Increasing Disorder only applies to closed systems. B. It is because the Law of Increasing Disorder doesn't apply to living things. C. It is because these things don't represent order. D. It is because the sun provides additional high-order energy to the world to create this order.

D

What would be the chemical formula of the ionic compound between calcium and bromine? A. CaBr B. Ca2Br2 C. Ca2Br D. CaBr2

D

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? Select one: 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 temperature of the room would stay the same because internal energy is conserved. 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 room would cool down because the electrical potential energy from the outlet decreases the ambient thermal energy in the room.

A

Can sulfur be considered a compound and why? A. No, it is composed of only one type of atom B. Yes, it is composed of only one type of atom C. No, it is composed of more than one type of atom D. Yes, it is composed of more than one type of atom

A

How many double bonds exist between carbon atoms in these saturated fatty acids? A. Zero B. One C. One or More D. Two

A

The diagrams above show how a photon can be emitted from three different semiconductors, one red, one yellow, and one blue. Which emits a red photon? A. The first B. The second C. The last

A

The graphs below show energy as a function of time for several different reactions. Which of the reactions shown below would end up absorbing energy from the surroundings? A. B. C. D. E.

A

When you compare the band gap for a red and a blue LED, what is true? Select one: A. The red LED has the smallest band gap. B. The blue LED has the smallest band gap. C. The band gaps are equal as long as the battery powering them is the same. D. The color of light doesn't have anything to do with the band gap.

A

How does a catalyst affect a reaction? Select one: A. It raises the activation entropy B. It changes anti-bonding orbitals into bonding orbitals C. It lowers the band gap D. It lowers the activation energy E. It increases the energy of the transition state

D

How many nonmetals atoms (bromine) are needed to take all of the electrons that the metal atoms (calcium) want to give? A. 1 Bromine atom, 1 Calcium atom B. 2 Bromine atoms, 2 Calcium atoms C. 1 Bromine atom, 2 Calcium atoms D. 2 Bromine atoms, 1 Calcium atom

D