Chem. 백점 히어위 고

1-7. The first five ionization energies of an unknown element are listed in the table above. Which of the following statements correctly identifies the element and cites the evidence supporting the identification?

B. Al, because of the large difference between the third and fourth ionization energies.

2-6. Which of the following Lewis electron-dot diagrams represents the molecule that is the most polar?

B. Br-F 연결된거

1-6. the masses of carbon and hydrogen in samples of four pure hydrocarbons are given above. The hydrocarbon in which sample has the same empirical formula as propene, C3H6 ?

B. Sample B

3-23. Which of the following most likely describes the solid represented in the diagram above?

C. It is a brittle, water-soluble electrolyte that is a poor thermal and electrical conductor as a solid.

The ionization energies of an unknown element, X, are listed in the table above. Which of the following is the most likely empirical formula of a compound formed from element X and phosphorus, P?

C. X3P2

4-9. A mixture of tow gases, 0.01 mol of C4H10(g) and 0.065mol of O2(g), is pumped into a cylinder with a movable piston, as shown above. The mixture, originally at 200 celsius and 1.0 atm, is sparked and the reaction represented below occurs. Which of the following is true after the product gases return to the original temperature and pressure, and why will the change occur? (Assume all gases behave ideally.)

A. The piston will be higher than its original position, because the cylinder will contain a greater number of gas molecule.

3-1. Of the three solutions listed in the table above, which one, if any, has the greatest electrical conductivity and why?

B. 0.1 M KI (aq) because KI completely dissociates in water to produce ions.

4-3. If 3.8 g of Cu3(PO4)2(s) was recovered from step 1, what was the approximate [Cu2+] in the original solution? (The molar mass of Cu3(PO4)2 is 381 g/mol.)

B. 0.30 M

4-5. In a one-person spacecraft, an astronaut exhales 880 g of CO2 (g) (molar mass 44 g/mol) per day. To prevent the buildup of CO2 (g) in the spacecraft, a device containing LiOH(s) is used to remove the CO2 (g), as represented by the equation above. What mass of LiOH(s) (molar mass 24 g/mol) is needed to react with all fo the CO2(g) produced by an astronaut in one day?

B. 240 g

4-6. A mixture of CO(g) and O2(g) is placed in a container, as shown above. A reaction occurs, forming CO2(g). Which of the following best represents the contents of the box after the reaction has proceeded as completely as possible? colored circle = C / white circle = O

B. CO2 4개 / O2 1개

4-8. A mixture of H2(g) and O2(g) is placed in a container as represented above. the H2(g) and O2(g) react to form H2O(g). Which of the following best represents the container after the reaction has gone to completion? colored circle = H / white circle = O

B. H2O 4개 / O2 2개

3-20. Ne, HF, C2H6, CH4. Which of the substances listed above has the highest boiling point, and why?

B. HF, because its molecules form hydrogen bonds.

3-13. On the basis of molecular structure and bond polarity, which of the following compounds is more likely to have the greatest solubility in water?

C. NH3

3-16. Based on Coulomb's law and the information in the table above, which of the following anions is most likely to have the strongest interactions with nearby water molecules in an aqueous solution?

C. S^2-

1-2. The mass of the Cu(s) produces in step 3 was slightly more than the mass predicted from 3.8 g or Cu3(PO4)2 recovered from step 1. Which of the following could a account for the discrepancy in the yield of Cu(s) from step 3 ?

C. Some unreacted Zn(s) was mixed in with the Cu(s).

4-2. Which of the following is the molecular formula of the unknown compound?

D. C4H8O2

3-22. Equal volumes of solutions in two different vessels are represented above. If the solution represented in vessel 1 is KCl(aq), then the solution represented in vessel 2 could be an aqueous solution of

D. CaCl2 with twice the molarity of the solution in vessel 1

3-17. Based on the structures shown above, which of the following statements identifies the compound with the higher boiling point and provides the best explanation for the higher boiling point?

D. Compound 2, because it forms hydrogen bonds, whereas compound 1 does not

4-7. Which of the following particle diagrams best represents the products when four molecules of H2O2(l) decompose into water and oxygen gas at room temperature? colored circle = H / white circle = O

D. H2O 4개 / O2 2개

3-21. Based on the diagram above, which of the following best helps to explain why MgO(s) is not able to conduct electricity, but MgO(l) is a good conductor of electricity?

D. MgO(s) consists of separate Mg2+ ions and O2- ions held in a fixed lattice, but in MgO(l) the ions are free to move and conduct electricity.

3-26. Three substances were studied in the laboratory, and the data in the table above were collected. Based on the data, which of the following shows the type of bonding in each substance?

D. Network covalent / Metallic / Ionic

3-11. Which of the following best helps to explain why CCl4 is a liquid whereas Cl4 is a solid when both are at 25 celsius.

D. The London dispersion forces are stronger in Cl4 than in CCL4 because Cl4 has a more polarizable electron cloud than CCl4

2-9. The table above provides some information about two types of steel, both of which are alloys of iron and carbon. Which of the following best helps to explain why high-carbon steel is more rigid than low-carbon steel?

D. The additional carbon atoms within the alloy make it more difficult for the iron atoms to slide past one another.

1-8. a sample of a solid labeled as NaCl may be impure. A student analyzes the sample and determines that it contains 75 percent chlorine by mass. Pure NaCl (s) contains 61 percent chlorine by mass. Which of the following statements is consistent with the data?

D. The sample contains NaCl(s) and LiCl(s).

3-10. The structural formulas for two isomers of 1, 2-dichloroethene are shown above. Which of the two liquids has the higher equilibrium vapor pressure at 20 celsius, and why?

D. The trans-isomer, because it has only London dispersion forces, whereas the cis-isomer also has dipole-dipole interactions

3-28. A balloon filled with 0.25 mol of He(g) at 273 K and 1 atm is allowed to rise through the atmosphere. Which of the following explains what happens to the volume of the balloon as it rises from ground level to an altitude where the air temperature is 220 K and the air pressure is 0.1 atm?

A. The volume will increase because the decrease in air pressure will have a greater effect than the decrease in temperature.

3-4. At 298 K and 1 atm, Br2 is a liquid with a high vapor pressure, and Cl2 is a gas. Those observations provide evidence that under the given conditions, the

A. forces among Br2 molecules are stronger than those among Cl2 molecules.

1-1. which of the following correctly compares periodic properties of two elements and provides an accurate explanation for that difference?

D. The atomic radium of Cl is smaller than that of S because Cl has a larger nuclear charge than S does.

1-9. Which of the following best helps to explain why Na (s) is more reactive with water than Mg (s) is?

D. The first ionization energy of Na is less than that of Mg.

3-14. Which compound, chloroacetic acid or iodoacetic acid, most likely has the lower boiling point, and why?

A. Chloroacetic acid, because the London dispersion forces among its molecules are weaker.

3-3. The Maxwell-Boltzmann distributions of molecular speeds in samples of two different gases at the same temperature are shown above. Which gas has the greater molar mass?

A. Gas A

2-1. Which of the following has the bonds arranged in order of decreasing plarity?

A. H-F > N-F > F-F

1-3. If a pure sample of an oxide of sulfur contains 40. percent sulfur and 60. percent oxygen by mass, then the empirical formula of the oxide is

A. SO3

3-27. Which of the following is true after the product gases return to the original temperature and pressure, and why will the change occur? (Assume all gases behave ideally.)

A. The piston will be higher than its original position, because the cylinder will contain a greater number of gas molecules.

2-7. Of the following diagrams, which best represents the structure of solid KF ?

B. + and - alternate 하는 diagram

4-4. Li3N(s) + 2 H29g) --> LiNH2(s) + 2 LiH(s) H = -192 kJ/mol Because pure H2 is a hazardous substance, safer and more cost effective techniques to store it as a solid for shipping purposes have been developed. One such method is the reaction represented above, which occurs at 200 celsius. When 70. g of Li3N(s) (molar mass 35 g/mol) reacts with excess H2(g), 8.0 g of LiH(s) is produced. the percent yield is closest to

B. 25%

2-3. The structural formula of the glycinium cation is shown above. Arrows indicate the pKa values for the labile proton in the molecule. Which of the following is true about the geometry of the glycinium cation?

B. Both C atoms and both O atoms lie in the same plane.

2-2. Which of the following can be inferred from the diagram above that shows the dependence of potential energy on the internuclear distance between two atoms?

B. The atoms form a bond with a bond length of 75 pm.

3-8. A sealed 10.0 L flask at 400 K contains equimolar amounts of ethane and propanol in gaseous from. Which fo the following statements concerning the average molecular speed of ethane and propanol is true?

B. The average molecular speed of ethane is greater than the average molecular speed of propanol.

2-4. The structural formula of the glycinium cation is shown above. Arrows indicate the pKa values for the labile proton in the molecule. Which is the approximate H-O-C bond angle in the glycinium cation?

C. 105 degree

3-12. When 4.0 L of HE(g), 6.0 L of N2(g), and 10. L of Ar(g), all at 0 celsius and 1.0 atm, are pumped into an evacuated 8.0 L rigid container, the final pressure in the container at 0 celsius is

C. 2.5 atm

3-19. If the absorbance of the mixture is 0.20 at 453 nm, how many moles of Fe3+ (aq) were present in the 100. mL sample? (Assume that any volume change due to adding the KSCN(s) is negligible.)

C. 4 x 10^-6 mol

1-5. The compound CCl4 is nonflammable and was once commonly used in fire extinguishers. On the basis of the periodic properties, which of the following compounds can most likely be used as a fire-resistant chemical?

C. CBr4

3-24. A 1.0 L sample of a pure gas is found to have a lower pressure than that predicted by the ideal gas law. The best explanation for the observation is that the molecules of the gas

C. are attracted to each other and do not exert as much force on the container walls as they would if they had no mutual attractions

3-2. Solid carbon tetrachloride, CCl4 (s), is represented by the diagram above. The attractions between the CCl4 molecules that hold the molecules together in the solid state are best identified as

C. intermolecular attractions resulting from temporary dipoles

3-5. Compared to the equilibrium vapor pressure of CH3OH(l) at 300 K, the equilibrium vapor pressure of C2H5OH(l) at 300 K is

C. lower, because London dispersion forces among C2h5OH molecules are greater than those among CH3OH molecules

4-1. Which of the following best describes the change that takes place immediately after the CH3OH(l) is introduced into the previously evacuated vessel?

D. A physical change takes place because intermolecular attractions are overcome.

3-9. Based on the information in the table above, which of the compounds has the highest boiling point, and why?

D. Propanoic acid, because it can form intermolecular hydrogen bonds

3-7. Based on the structural formulas, which of the following identifies the compound that is more soluble in water and best helps to explain why?

D. Propanol, because its molecules can form hydrogen bonds with water molecules but those of ethane cannot.

3-18. A student is given a sample of a pure, white crystalline substance. Which of the following would be most useful in providing data to determine if the substance is an ionic compound?

D. Testing the electrical conductivity of an aqueous solution of the substance.

2-5. in the reaction represented above, what is the hybridization of the C atoms before and after the reaction occurs?

D. before: sp^2 / after: sp^3

3-6. A 1.0 mol sample of He (g) at 25 celsius is mixed with a 1.0 mol sample of Xe (g) at 50 celsius. Which of the following correctly predicts the changes in average kinetic energy and the average speed of the Xe (g) atoms that will occur as teh mixture approaches thermal equilibrium?

D. will decrease / will decrease

2-8. NH3 reacts with BF3 to form a single species. Which of the following structural diagrams is the most likely representation of the product of the reaction?

D. 가운데가 H-N-B-F 로 되어있는거.

3-25. The ideal gas law best describes the properties of which of the following gases at 0 celsius and 1 atm?

D. N2

3-15. The diagram above represents a particle in aqueous solution. Which of the following statements about the particle is correct?

B. The particle must be an anion because the positive end of each water molecule is pointed toward it.