27. Which of the following anions is the most basic?
(A)
(B)
(C)
(D)
(E)

23. A compound is composed of element X and hydrogen. A mass analysis shows the compound contains 82.35% of X, with three times as many hydrogen atoms as X atoms per molecule. Which element is X? (atomic mass: B = 10.81, C = 12.01, N = 14.01, Al = 26.98, P = 30.97) (A) B (B) C (C) N (D) Al (E) P

24. Which of the following statements is incorrect? (A) Heteronuclear linear molecules can have a net dipole moment. (B) A molecular dipormenant is the dipole moment of the molecular taken as a whole. (C) Ionic bonding results from the transfer of electrons from one atom to another. (D) A molecule with polar bonds must be polar. (E) The distribution of electrons in a polar bond is closer to the more electronegative element.

25. Regarding to the concept of reduction and oxidation, which of the following statements is true? (A) All chemical changes is accompanied by reduction and oxidation. (B) When the atom is oxidized, the size becomes larger. (C) The oxidizing agent is electron donor. (D) Reduction and oxidation can occur independently of each other. (E) Reduction and oxidation describe the gain and loss of electron(s), respectively.

26. You have immersed electrodes of a light bulb in a solution of H2SO4 such that the light bulb is on. You add a dilute solution and the bulb grows dim. Which of the following molecule could be in the solution? (A) Cu(NO3)2 (B) K2SO4 (C) NaNO3 (D) ZnCl2 (E) Pb(NO3)2

28. Which of the following element or ions is the largest in size? (A)(B)(C) Ne (D) (E)

29. Which of the following molecules has the largest dipole moment? (A) CO2 (B) Cl2 (C) XeF4 (D) SF4 (E) BF3

30. I. The hybridization of boron in BF3 is sp3.II.The molecule of is polar.III. The bond order of N2 molecule is two.IV. The molecule of HCN has one pi bond and two sigma bonds.Which is true?(A) All four statements are correct. (B) II is incorrect.(C) I and IV are incorrect. (D) II and III are incorrect.(E) All four statements are incorrect.

31. The velocities of drivers A and B are shown as functions of time in the figure below. Driver B starts her car at the instant driver A passes her. At which moment on the graph are drivers A and B side by side? (A) 0 s, 2 s (B) 0 s, 4 s (C) 2 s, 4 s (D) 2 s, 6 s (E) 4 s, 6 s

32. A uniform cord has the mass per unit length λ and it is arranged as that shown in the figure. Here the tension is maintained by suspending an object of mass M from one end. What is the speed of a pulse on the cord if the tension force is not affected by the mass of the cord? (Gravitational acceleration is g) (A) (B) (C) (D) (E)

33. As shown in figures (a) and (b), a constant force F is applied to the two contact blocks in both cases. In figure (a), block A pushes against block B with a 20 N force directed horizontally to the right. In figure (b), block A pushes against block B with a 10 N force directed horizontally to the left. The total mass of two blocks is 12 kg. Which of the following statement is correct? (Gravitational acceleration g = 10 m/s2 )  (A) The magnitude of F is 20 N. (B) The mass ratio between block A and B is 2. (C) The acceleration in (a) is 1.5 m/s2. (D) The acceleration in (b) is 2.5 m/s2. (E) The mass of block A is 8 kg.