First 6 Questions on Lessons 18-25/Unit 3

Each molecule of nitric acid has the formula HNO3 3. 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: 2000

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: Entropy must increase as a result of the reaction.

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: Have a higher conductivity rate

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: Metals resistance increases when temperature increases while a semi-conductors resistance decreases.

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: Neon Gas

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: The red LED has the smallest band gap

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

D: Oxygen Molecule

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: An ice cube floating in a sealed insulated container of water at zero degrees

In the equation C2H4 + 3O2 = ? CO2 + 2H2O, how many CO2 molecules are needed to balance the equation? Select one: A. 2 B. 3 C. 4 D. 5

A: 2

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: Brittle, transparent, electrically non-conducting solid

Which of the following is a correct and balanced equation showing the reaction of calcium and oxygen? (While several of the equations may be balanced, only one has the correct products and reactants as well as being correctly balanced.) A. Ca + O2 = CaO B. Ca + O2 = CaO2 C. 2Ca + O2 = 2CaO D. 4Ca + O2 = 2Ca2O E. Ca + O2 = Ca2O

C: 2Ca + O2 = 2CaO

Which of the equations below is balanced correctly? Select one: A. Mg + N2 = MgN3 B. 2P2 + O2 = P2v2O5 C. CH4 +2O2 = CO2 + 2H2O D. 2Zn + O2 = ZnO E. 2C + O2 = 2CO2

C: CH4 + 2O2 = CO2 + 2H2O

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: increases

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: Network Matter

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? Select one: 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 traveling on the level. When it climbs up a hill, however, the efficiency drops because of the changing gravitational potential energy

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.

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: Chemical potential energy is converted into thermal energy resulting in an increase in entropy

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: because metals have empty, overlapping orbitals for their electrons

TorF: Metals have higher ionization energies than non-metals do.

False

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: Gravitational Potential Energy

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: The magnesium atoms valence electrons are effectively transferred to oxygen

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: 100% conversion of electricity to ambient temperature thermal energy

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: It lowers the activation energy