Chemistry — High school and intro college

Las preguntas del cuestionario

1. 1. London dispersion forces are caused by
   1. temporary dipoles created by the position of electrons around the nuclei in a molecule
   2. the three-dimensional intermolecular bonding present in all covalent substances
   3. the uneven electron-to-proton ratio found on individual atoms of a molecule
   4. the electronegativity differences between the different atoms in a molecule
2. 2. Carbon has an atomic radius of 77 pm and a first ionization energy of 1086 kJ/mol.
   1. 70 pm, 1402 kJ/mol
   2. 86 pm, 898 kJ/mol
   3. 135 pm, 523 kJ/mol
   4. 40 pm, 995 kJ/mol
3. 3. An unknown substance is found to have a high melting point. In addition, it is a poor conductor of electricity and does not dissolve in water. The substance most likely contains
   1. ionic bonding
   2. nonpolar covalent bonding
   3. covalent network bonding
   4. metallic bonding
4. 4. The net ionic equation expected when solutions of NH4Br and AgNO3 are mixed together is
   1. Ag+(aq) + Br-(aq) → AgBr(s)
   2. NH4+(aq) + Ag+(aq) → Ag(NH4)3+2(aq)
   3. Br-(aq) + NO3-(aq) → NO3Br(aq)
   4. NH4Br(aq) + NO3-(aq) → NH4NO3(aq) + Br-(aq)
5. 5. The symbol for antimony is
   1. W
   2. Sb
   3. Fe
   4. An
6. 6. A sealed, rigid container contains three gases: 28.0 g of nitrogen, 40.0 g of argon, and 36.0 g of water vapor. If the total pressure exerted by the gases is 2.0 atm, what is the partial pressure of the nitrogen?
   1. 0.33 atm
   2. 0.40 atm
   3. 0.50 atm
   4. 2.0 atm
7. 7. Monatomic ions of the representative elements are often
   1. very soluble
   2. very electronegative
   3. isoelectronic with a noble gas
   4. highly colored
8. 8. Hund's rule requires that
   1. no two electrons can have the same four quantum numbers
   2. no two electrons with the same spin can occupy an orbital
   3. no two electrons can occupy separate orbitals
   4. no two electrons can pair up if there is an empty orbital at the same energy level available
9. 9. All of the following ions have the same electron configuration except
   1. Rb+
   2. Se2-
   3. As5+
   4. Sr2+
10. 10. Sulfurous acid is a weak acid, while sulfuric acid is a much stronger acid because
    1. the O–H bonds in sulfuric acid are much weaker than in sulfurous acid due to the electron withdrawing of the oxygen atoms on sulfuric acid
    2. sulfuric acid has more oxygen atoms in its formula
    3. the sulfur in sulfuric acid is more electronegative than the sulfur in sulfurous acid
    4. sulfuric acid has the hydrogen atoms bound directly to the sulfur atom
11. 11. What is the molarity of a sodium hydroxide solution that requires 42.6 mL of 0.108 M HCl to neutralize 40.0 mL of the base?
    1. 0.0641 M
    2. 1.64 M
    3. 0.115 M
    4. 0.400 mol/L
12. 12. Which of the following substances has an asymmetrical molecular structure?
    1. SF4
    2. PCl5
    3. BF3
    4. CO2
13. 13. Hydrogen fluoride, HF, is a liquid at 15°C. All other hydrogen halides (represented by HX, where X is any other halogen) are gases at the same temperature. Why?
    1. Fluorine has a very high electronegativity; therefore the H-F bond is stronger than any other H-X bond.
    2. HF is smaller than any other H-X molecule; therefore it exhibits stronger London dispersion forces.
    3. The dipoles in a HF molecule exhibit a particularly strong attraction force to the dipoles in other HF molecules.
    4. The H-F bond is the most ionic in character compared to all other hydrogen halides.
14. 14. The reaction of Br2(g) with Cl2(g) to form BrCl(g) has an equilibrium constant of 15.0 at a certain temperature. If 10.0 grams of BrCl is initially present in a 15.0-liter reaction vessel, what will the concentration of BrCl be at equilibrium?
    1. 3.8 × 10^-3 mol/L
    2. 5.77 × 10^-3 mol/L
    3. 1.97 × 10^-3 M
    4. 9.9 × 10^-4 M
15. 15. A sample of liquid NH3 is brought to its boiling point. Which of the following occurs during the boiling process?
    1. The N-H bonds within the NH3 molecules break apart.
    2. The overall temperature of the solution rises as the NH3 molecules speed up.
    3. The amount of energy within the system remains constant.
    4. The hydrogen bonds holding separate NH3 molecules together break apart.
16. 16. A student has a liter of a 0.100 M solution of a strong acid. To prepare a buffer, this should be mixed with
    1. a strong acid
    2. a weak acid
    3. a weak base
    4. a strong base
17. 17. Which of the following indicates that a reaction is spontaneous?
    1. at equilibrium there are more products than reactants
    2. the value of ΔG° is greater than zero
    3. the value of ΔS° is greater than zero
    4. the value of Keq is less than one
18. 18. Which of the following is expected to have the largest bond polarity?
    1. S–O
    2. P–F
    3. C–B
    4. C–N
19. 19. A mechanism is a sequence of elementary reactions that add up to the overall reaction stoichiometry. A substance that is produced in one elementary reaction and consumed in another is called
    1. a catalyst
    2. an intermediate
    3. a reactant
    4. a complex
20. 20. Approximately how many half-lives will it take to reduce 10.0 kg of a radioactive substance to 1.0 microgram of that substance?
    1. 8
    2. 13
    3. 29
    4. 34
21. 21. S(s) + O2(g) → SO2(g)
    1. either S(s) or O2(g) will be completely used up
    2. Q must be close to 1.0 since there is one mole of gas on each side of the equation
    3. this reaction goes to completion
    4. adding O2 will change the equilibrium constant
22. 22. Three half-lives after an isotope is prepared,
    1. 25% of the isotope is left
    2. 25% of the isotope decayed
    3. 12.5% of the isotope is left
    4. 12.5% of the isotope decayed
23. 23. The rate, r, of a zero-order chemical reaction A → B can be expressed as which of the following?
    1. r = k ln[A]
    2. r = k [A]^2
    3. r = k [A]
    4. r = k
24. 24. Infrared (IR) spectroscopy is useful for determining certain aspects of the structure of organic molecules because
    1. all molecular bonds absorb IR radiation
    2. IR peak intensities are related to molecular mass
    3. most organic functional groups absorb in a characteristic region of the IR spectrum
    4. each element absorbs at a characteristic wavelength
25. 25. What is the maximum number of phases that can be at equilibrium with each other in a three component mixture?
    1. 2
    2. 3
    3. 4
    4. 5
26. 26. When the following equation is balanced, which of the following is true?
    __ MnO4− + __ I− + __ H+ <-> __ Mn2+ + __ IO3− + __ H2O
    1. The I− : IO3− ratio is 3:1.
    2. The MnO4- : I- ratio is 6:5.
    3. The MnO4- : Mn2+ ratio is 3:1.
    4. The H+ : I− ratio is 2:1.
27. 27. The equation ΔH = ΔU + PΔV is applicable
    1. always
    2. only for constant pressure processes
    3. only for constant temperature processes
    4. only for constant volume processes
28. 28. Nitronyl nitroxides are stable radicals in which the unpaired electron is coupled to two equivalent nitrogen nuclei. How many lines will appear in the EPR spectrum of a solution of a rigid nitronyl nitroxide diradical with J << a?
    1. 3 lines
    2. 9 lines
    3. 5 lines
    4. 7 lines
29. 29. Cobalt-60 is used in the radiation therapy of cancer and can be produced by bombardment of cobalt-59 with which of the following?
    1. Neutrons
    2. Alpha particles
    3. Beta particles
    4. X-rays
30. 30. Which of the following is required for both paramagnetism and ferromagnetism?
    1. Strong oxidizing conditions
    2. Low-spin electron configuration
    3. Metallic physical properties
    4. Unpaired electrons

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