15. The rate constant for the beta decay of thorium-234 is 2.88×10^-2 /day. What is the half-life of this nuclide?
(A)53.1days
(B)1.22days
(C)24.1days
(D)101days
(E)0.693days

11. Which of the following is true for the cell shown here? (A)The electrons flow from the cathode to the anode. (B)The electrons flow from the zinc to the chromium. (C)The electrons flow from the chromium to the zinc. (D)The chromium is oxidized. (E)The zinc is reduced.

【已刪除】複選題12. Determine △G for a cell that utilizes the following reaction:  The standard reduction for the chlorine gas is 1.360 volts and the standard reduction for the bromine liquid is 1.077 volts. (A)82.5kJ (B)54.6kJ (C)27.3kJ (D)236kJ (E)471kJ

13. Give the number of geometrical isomers for the octahedral compound [MA2B2C2] where A, B and C represent ligands. (A)1 (B)2 (C)3 (D)4 (E)5 .

14. Which of the following is paramagnetic? (A)[Zn(H2O)6]2+ (B)[Co(NH3)6]3+ (strong field) (C)[Cu(CN)3]2- (D)[Mn(CN)6]2- (strong field) (E)non of these

16. Which of the following would not be expected to undergo disproportionation?  (A)Cl2(B)(C)(D)(E)

17. Which of the following oxides is amphoteric? (A) Al2O3 (B)B2O3 (C)In2O3 (D)Tl2O3 (E)Tl2O

18. The ionization constants for the diprotic acid H2S are 1.0×10-7 and 1.3×10-13. For 0.1molar solutions of sodium sulfide and sodium hydrogen sulfide, which of the following is true? (A) The solutions are neutral. (B)The sodium sulfide solution is the most basic. (C)Both the solutions are acidic. (D)The sodium hydrogen sulfide solutions is the most basic. (E)Both solutions have the same pH.

19. For the reaction system N2O4(g)≒2NO2(g) at 90°C, Kc = 0.27. For this system, what is Kp? (A) ＞ 0.27 (B)＜ 0.27 (C) = 0.27 (D)We can not determine Kp without additional data. (E)none of these

20. A second order reaction starts with an initial concentration of 0.020M of the reactant. If the rate constant is 10/(M. .), calculate the time required to decrease the initial concentration to 0.005M. (A)0.069s (B)10s (C)15s (D)0.139s (E)20s.

1.A 300N weight, 5m long rigid uniform ladder is leaning against a smooth vertical wall. A 750N weight man stands on a rung 4m up along the ladder from its base as shown in fig.1. What is the minimum coefficient of the statical friction between the ladder and the floor required to keep the system in equilibrium? The angle is 53.1° on a horizontal beam. (cos53.1° = 0.6, sin53.1° = 0.8) (A)0.22 (B)0.42 (C)0.46 (D)0.54 (E)1.90