5. For which one of the following reactions is the value of ∆Ho rxn equal to ∆Ho f for the product?
(A)2Ca_(s) + O_2(g)→ 2CaO_(s)
(B)C₂H_2(g) + H_2(g)→ C₂H_4(g)
(C) 2C(graphite) + O_2(g)→ 2CO_(g)
(D)3Mg_(s) + N_2(g)→ Mg₃N_2(s)
(E) None of these

1. A correct name for Fe(NO₃)₂ is ________. (A)Iron nitrite(B)Ferrous nitrite(C)Ferric nitrite (D)Iron nitrate(E)Ferrous nitrate

2. A 0.8715 g sample of sorbic acid, a compound first obtained from the berries of a certain ash tree, is burned completely in oxygen to give 2.053 g of carbon dioxide and 0.5601 g of water. The empirical formula of sorbic acid is (A)CH₂O (B).C₃H₄O(C)CH₄O₃ (D)C₃H₄O₂(E)CH₄O₂

3. Which compound has the atom with the highest oxidation number? (A)CaS(B)Na₃N(C)MgSO₃ (D)Al(NO₂)₃(E)NaCl

4. Which of the following statements is false? (A)The density of a gas is directly proportional to the external pressure.(B)The density of helium gas is double that of hydrogen gas.(C)The density of a gas is indirectly proportional to the temperature in Kelvin. (D)All gases have the same density at STP.(E) All the statements above are correct.

6. A mole of yellow photons of wavelength 527 nm has ________ kJ of energy. (A)165(B)227 (C) 4.56 × 10-46 (D)6.05 × 10-3 (E)527

 7. Using the following data reactions:Calculate the energy of an H–Cl bond.(A)770kJ(B)856 kJ(C)518 kJ (D)487 kJ(E)428 kJ 

 28. Which of the following has the greatest bond strength? (A)B₂(B)O₂⁻(C)CN⁻ (D)O₂⁺(E)H2

9. A salt, MY, crystallizes in a body-centered cubic structure with a Y⁻ anion at each cube corner and an M⁺ cation at the cube center. Assuming that the Y⁻ anions touch each other and the M⁺ cation at the center, and that the radius of Y⁻ is 158 pm, what is the radius of M⁺? (A)65.4 pm(B)116 pm(C)79.0 pm (D)41.1 pm(E)105.3 pm

10. When 0.014 mol of a weak acid HA is dissolved in enough water to make 1.0 L of solution, [H ⁺] is 1.8x10-3 M. Calculate the freezing point of this solution. Assume that the molarity concentration is equal to the molality concentration, and assume ideal behavior. *Kf (H₂O) is 1.86°C∙kg/mol. (A)-0.029°C(B)-0.026°C(C)-0.058°C (D)+0.029°C(E)+0.058°C

11. The kinetics of the reaction A + 3B→ C + 2D were studied and the following results obtained, where the rate law is: -∆[A]/ ∆t = k[A]n [B]m. For a run where [A]0= 1.0x10-3 M and [B]0= 5.0 M, a plot of ln[A] versus t was found to give a straight line with slope = -5.0x10-2 s -1 . For a run where [A]0= 1.0x10-3 M and [B]0= 10.0 M, a plot of ln[A] versus t was found to give a straight line with slope = -7.1x10-2 s -1 . Calculate the value of k (ignore units). (A)11(B)10(C)50 (D)1.1(E)22