13. According to Lenz's law, when changing the magnetic flux throu^i a coil, the direction of the induced current in a coil is such lhatit...
(A) opposes the change in magnetic flux.
(B) supports the change in m^netic flux.
(C) depends on the resistance of the coil.
(D) is unrelated to the magnetic flux. 也)aligns with the magnetic flux.

9. Which of the following statements about absolute pressure P, gauge pressure PG and atmospheric pressure P0is true? (A) P is the same as PG at 273 K. (B) P0 + PG is the absolute pressure P. (C) Gauge pressure PG is always positive. (D) Absolute pressure P is the atmospheric pressure P0 at 15°C. (E) None of the above.

10. Which of the following gases would exhibit a more narrow K^xweH-Boltzmann speed distribution at a given temperature? (A) Hydrogen (H2) (B) Oxygen (O2) (C) Nitrogen (N2) (D) Helium (He) (E) Argon (Ar)

11. Which of the following descriptions of electrons is correct? (A) Electrons are massless. (B) Electrons are positively charged. (C) Electrons can travel at the speed of light. (D) Electrons obey the Pauli exclusion principle. (E) None of the above.

12. Under what condition does the magnetic force on a charged particle perform work? (A) When the particle moves parallel to the magnetic field. (B) When the particle moves perpendicular to the magnetic field. (C) When the particle moves at an angle to the magnetic field. (D) When lhe magnetic field is non-uniform. (E)None of tiie above.

14. See the right figure, there is a metallic sphere, on 的ich a constant electric potential is applied, A chained particle moves fh＞m point A to point B through three different kinds of paths denoted as I, II, and III. Through which path does the particle gain the most electric eneigy?(A) I (B)II (C) III (D) All the same (E) It depends on the sign of the charge.

15. Refer to the figure. A conducting loop (square coil of wire) is pulled at constant velocity through a uniform magnetic field entering the plane. Which of the following statements is correct?(A) Current is induced in the loop in the clockwise direction. (B) Current is induced in the loop in the counterclockwise  direction. (C) Alternating current is induced in the loop.  (D) Charge separation occurs； negative chafes are accumulated at the bottom edge. (E) Charge separation occurs； negative charges are accumulated at the top edge.

16. The coordination geometry of Cr(NO)4 is_____  . (A) tetrahedral (B)trigonal pyramidal (C) see-saw (D) square planar (E) none of tiie above

17. What type of hi^h energy bonds are found in ATP and ADP? (A) ca^oxylic anhydride (B) phosphodiester (C) thioester (D) phosphoanhydride (E) amine

18. Consider the second-order reaction A → products, Mich has a first half-life of 25 s.If the concentration of A after 15.6 s is 0.36 M, determine the initial concentration of A. (A) 0.58 M (B)026M (C) 0.53 M (D)0.14M (E)0.16M

19. Which of the following is the reason for minimum chemical interferences in inductively-coupled plasma? (A) Zeeman efiect correction (B) high ionization efficiency (C) high temperature (D) large number of emission lines (E) none of the above