27. Which ion is planar?
(A)
(B)
(C)
(D)
(E)

23. Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass? (A) water gets into the solvent after the freezing point of the pure solvent is determined (B) some of the solute molecules break apart (C) the mass of solvent is smaller than determined from the weighing (D) while adding the solute, the technician spilled some of it on the lab bench (E) all of these

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

25. The phrase "a solid dissolved in a gas" describes a(n) (A) foam (B) sol (C) emulsion (D) aerosol (E) none of these

26. Select the correct molecular structure for . (A) pyramidal (B) tetrahedral (C) square planar (D) octahedral (E) none of these

28. The bond angles about the carbon atom in the formaldehyde molecule, H2C = O, are about (A) 120°(B) 60°(C) 109°(D) 180°(E) 90°

29. How many of the following molecules and ions are linear? (A) 0(B) 1 (C) 2 (D) 3(E) 4

30. Consider the following molecules, and select the molecule(s) that fit the given statement. I: BF3, H: CHBr3, M: Br2, TV: XeCl2, V: CO, VI: SF4These molecules violate the octet rule. (A) I,lI, IV (B) I, III, IV, VI (C) III, V, VI (D) I, IV, VI (E) I, II, IV, VI

31. Consider the molecular-orbital description of the anion. Which of the following statements is false? (A) is paramagnetic (B) is isoelectronic with CO (C) the bond energy in is greater than the bond energy in (D) the bond order in is 2 (E) II of these statements are false

32. For how many of B2, C2, P2, and F2 does bond order decrease if one electron is removed from the neutral molecule? (A) 0(B) 1 (C) 2 (D) 3 (E) 4

33. Order the following from shortest to longest bond: C2, B2, H2, N2 (A) H2, N2, C2, B2 (B) N2, C2, B2, H2 (C) C2, N2, H2, B2 (D) C2, B2, H2, N2 (E) none of these