5. At elevated temperatures, sodium chlorate decomposes to produce sodium chloride and oxygen gas. A 0.8765-g sample of impure sodium chlorate was heated until the production of oxygen gas ceased. The oxygen gas collected over water occupied 57.2 mL at a temperature of 22°C and a pressure of 734 torr. At 22°C the vapor pressure of water is 19.8 torr. The mass percentage of sodium chlorate in the original sample is_____.
(A) 46.5%
(B) 18.0%
(C) 23.3%
(D) 76.7%
(E) 53.5%

1. A 25.00-g sample of a solid is placed in a graduated cylinder, and then the cylinder is filled to the 50.0-mL mark with benzene. The mass of benzene and solid together is 58.80 g. Assuming that the solid is insoluble in benzene and that the density of benzene is 0.880 g/cm3, please calculate the density of the solid to be _____g/dm3.(A) 2160(B) 2200(C) 2.16(D) 2.2(E) 2

2. Which one of the following statements is incorrect? (A) Sodium arsenate has its formulas of Na3AsO4. (B) A halogen with 85 protons and 85 electrons is At. (C) A possible name for FeBr3 is ferrous bromide. (D) The systematic name for Pb(C2H3O2)2·3H2O is lead (II) acetate trihydrate (E) The systematic name for K2O2 is potassium peroxide

3. Ten tablets with a total mass of 0.5894 g contained saccharin (C7H5NO3S) and were dissolved in water. The saccharin was oxidized to convert all the sulfur to sulfate ion, which was precipitated by adding an excess of barium chloride solution. The mass of barium sulfate obtained was 0.5032 g. The average mass percent of saccharin in the tablets is thus_____. (A) 33.00% (B) 0.052% (C) 53.10% (D) 95.95% (E) 67.00%

4. Consider three identical flasks filled with different gases: Flask A, CO at 760 torr and 0°C； Flask B, N2 at 250 torr and 0°C； Flask C, H2 at 100 torr and 0°C. Which one of the following statements is consistent with the conditions described above? (A) Ranking the gases in order of increasing average kinetic energy: Flask A＞ Flask B ＞ Flask C (B) Ranking the gases in order of increasing average velocity: Flask A ＞ Flask B ＞ Flask C (C) Ranking the gases in order of increasing average velocity: Flask B ＞ Flask A ＞ Flask C (D) Ranking the gases in order of increasing average kinetic energy: Flask A = Flask B = Flask C (E) Ranking the gases in order of increasing average kinetic : Flask A ＜ Flask B ＜ Flask C

6. Consider the dissolution of CaCl2: CaCl2(s)→Ca2+(aq) +2Cl ̄(aq), △H = -81.5 kJ. An 11.0-g sample of CaCl2 is dissolved in 125 g water, with both substances at 25°C. Assuming no heat loss to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/°C g, the final temperature of the solution is _____°C. (A) 39.2(B) 26.8(C) 14.2(D) 23.7(E) 30.0

7. Which one of the following statements is incorrect? (A) An unknown nonmetal element with a valence electron configuration of ns2np4 has a smaller radius than barium. (B) The set of quantum numbers, n = 4, l = 3, ml = 4 is not allowed in the hydrogen atom. (C) A certain oxygen atom with the electron configuration of 1s22s22px22py2 has no unpaired electrons. (D) The order of increasing first ionization energy among K, Br, Ni is: Br ＜ Ni ＜K (E) (Kr)5s24d105p5 is the expected ground-state electron configuration for the element with one unpaired 5p electron that forms a covalent compound with fluorine.

8. For the transition of n = 3 →n = 2 to occur in the hydrogen atom, the wavelength of the resulting emitted light is _____ nm.(A) 121.6(B) 656.7 (C) 1876(D) 486.4(E) 48.64

9. Which one of the following statements is correct? (A) SO4 is more energetically stable than XeO4. (B) The order of increasing ionization energy in CI+ ＞ CI ＞ Se ＞ Se- is valid. (C) SeO3 has a T shape structure. (D) N2O is a nonpolar molecule. (E) The AsF5 molecule has a square pyramidal structure.

10. Consider the following reaction: H2C=CH2(g) + F2(g)→H2FC-CFH2(g), △H = -549 kJ. Please estimate the carbon-fluorine bond energy to be _____ kJ/mol given that the C-C bond energy is 347 kJ/mol, the C=C bond energy is 614 kJ/mol, and the F-F bond energy is 154 kJ/mol. (A) 239 (B)-184(C) -92(D) -327(E) 485

11. Consider three molecules: A, B, and C. Molecule A has a hybridization of sp3. Molecule B has two more effective pairs (electron pairs around the central atom) than molecule A. Molecule C consists of two σ bonds and two π bonds. Thus, which one of the following statements relating to A, B and C is incorrect? (A) Molecule A has a tetrahedral arrangement of electron pairs. (B) Molecule B has a square planar structure. (C) Molecule B has a bond angle of 109.5°. (D) The structure of HCN is similar to C. (E) Molecule C is consistent with a linear arrangement of electron pairs exhibiting sp hybridization.