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

19. The valence electron configuration of an element is . To which group does X belong? (A) Group 3A (B) Group 4A (C) Group 5A (D) Group 6A (E) Group 7A

20. In a 0.1 molar solution of NaCl in water, which of the following will be closest to 0.1? (A) the mole fraction of NaCl (B) the mass fraction of NaCl (C) the mass percent of NaCl (D) the molality of NaCI (E) all of these are about 0.1

21. Which statement about hydrogen bonding is true? (A) hydrogen bonding is the intermolecular attractive forces between two hydrogen atoms in solution. (B) the hydrogen-bonding capabilities of water molecules cause CH3CH2CH2CH3； to be more soluble in water than is CHJOH (C) hydrogen bonding of solvent molecules with a solute will not affect the solubility of the solute (D) hydrogen-bonding interactions between molecules are stronger than the covalent bonds within the molecule (E) hydrogen bonding arises from the dipole moment created by the unequal sharing of electrons in certain covalent bonds within a molecule

22. A solution of two liquids, A and B, shows negative deviation from Raoult's law. This means that (A) molecules of A interact strongly with other A-type molecules (B) the two liquids have a positive heat of solution (C) molecules of A interact weakly, if at all, with B molecules (D) the molecules of A hinder the strong interaction between B molecules (E) molecules of A interact more strongly with B than with A or and more strongly than B with B

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

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

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