40. Liquid A has vapor pressure x. Liquid B has vapor pressure y, and x ＞ y. What is the mole fraction of A in the liquid mixture if the vapor above the solution is 50% A?
(A) y/(2x + 2y)
(B) y/(x+ y)
(C) x/(2x + 2y)
(D) x/(x + y)
(E) none of these

36. The deciding factor that makes HF a weak acid is that (A) HF has a large bond energy (B) F2 has a small bond energy (C) the entropy for hydration of F- is a large negative value (D) the enthalpy of hydration ofF- is negative (E) F- has the largest ionization energy of all the halide ions

37. How many of the following statements are false? I：the Group 3A elements are all metals；II：Alkaline earth metals react less vigorously with water than do alkali metals；III：Salts can consist of hydrogen；IV：because Li is the strongest reducing agent among the alkali metals, it reacts most；V：quickly with water of the alkali metals (A) 1(B) 3 (C) 2(D) 4 (E) 0

38. The solubility of the salt. The osmotic pressure exhibited by a solution saturated with Mx,Ay, at 25℃ is 1.22 atm. Determine the values of x and y by assuming ideal behavior. (A) x = 1, y=3 (B) x= 27y = 5 (C) x = 1, y= 1 (D) x= 2 y = 3 (E) none of these

39. A cucumber is placed in a concentrated salt solution. What is most likely to happen? (A) salt will precipitate out (B) water will flow from the solution to the cucumber (C) salt will flow into the cucumber (D) water will flow from the cucumber to the solution (E) no change will occur

41. Rank the following compounds according to increasing solubility in water. I: CH3-CH2-CH2-CH3；ll: CH3-CH2-O-CH2-CH3； III: CH3-CH2-OH； IV:CH3-OH (A) I＜Il＜IV＜III (B) I ＜III＜IV＜I (C)I＜II＜III＜IV(D) III＜IV＜lI＜I (E) none is correct.

42. A liquid-liquid solution is called an ideal solution if I: it obeys PV = nRT； II: it obeys Raoult's law； IIl: solute-solute, solvent-solvent, and solute-solvent interactions are very similar； IV: solute-solute, solvent-solvent, and solute-solvent interactions are quite different. (A) II, IV (B) II, III (C) I, I (D) I, 1, 111(E) I, U, IV

43. How many unpaired electrons are found in (A) 0(B) 4 (C) 1(D) 5(E) 2

44. Which of the following statements about the complex ion Co(en)2Cl2+ (en = ethylenediamine, NH2CH2CH2NH2)is true? (A) the geometric isomers of the complex ion have identical chemical properties (B) the complex ion exhibits two geometric isomers (cis and trans) and two optical isomers (C) because en is a strong field ligand (large A), the complex ion is paramagnetic (D) the complex ion exhibits cis and trans geometric isomers, but no optical isomers (E) the complex ion contains Co(l)

45. The spectrochemical series is Which of the following complexes will absorb visible radiation of the highest energy? (A) (B) (C)(D)(E)

46. Which of the following complexes would be diamagnetic? (A)(B) (C) (D)(E) Fel(CO)5